merge branch "safe-string"

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@14705 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

147 files changed, 3311 insertions, 2448 deletions

diff --git a/.depend b/.depend
index 1d36a9c892..739a9bb191 100644
--- a/.depend
+++ b/.depend
@@ -43,12 +43,8 @@ parsing/ast_helper.cmo : parsing/parsetree.cmi parsing/longident.cmi \
     parsing/location.cmi parsing/asttypes.cmi parsing/ast_helper.cmi
 parsing/ast_helper.cmx : parsing/parsetree.cmi parsing/longident.cmx \
     parsing/location.cmx parsing/asttypes.cmi parsing/ast_helper.cmi
-parsing/ast_mapper.cmo : parsing/parsetree.cmi utils/misc.cmi \
-    parsing/location.cmi utils/config.cmi parsing/ast_helper.cmi \
-    parsing/ast_mapper.cmi
-parsing/ast_mapper.cmx : parsing/parsetree.cmi utils/misc.cmx \
-    parsing/location.cmx utils/config.cmx parsing/ast_helper.cmx \
-    parsing/ast_mapper.cmi
+parsing/ast_mapper.cmo : parsing/ast_mapper.cmi
+parsing/ast_mapper.cmx : parsing/ast_mapper.cmi
 parsing/lexer.cmo : utils/warnings.cmi parsing/parser.cmi utils/misc.cmi \
     parsing/location.cmi parsing/lexer.cmi
 parsing/lexer.cmx : utils/warnings.cmx parsing/parser.cmx utils/misc.cmx \
@@ -148,9 +144,9 @@ typing/btype.cmo : typing/types.cmi typing/path.cmi utils/misc.cmi \
     typing/ident.cmi typing/btype.cmi
 typing/btype.cmx : typing/types.cmx typing/path.cmx utils/misc.cmx \
     typing/ident.cmx typing/btype.cmi
-typing/cmi_format.cmo : typing/types.cmi utils/misc.cmi parsing/location.cmi \
+typing/cmi_format.cmo : typing/types.cmi parsing/location.cmi \
     utils/config.cmi typing/cmi_format.cmi
-typing/cmi_format.cmx : typing/types.cmx utils/misc.cmx parsing/location.cmx \
+typing/cmi_format.cmx : typing/types.cmx parsing/location.cmx \
     utils/config.cmx typing/cmi_format.cmi
 typing/cmt_format.cmo : typing/types.cmi typing/typedtreeMap.cmi \
     typing/typedtree.cmi utils/misc.cmi parsing/location.cmi \
@@ -160,12 +156,12 @@ typing/cmt_format.cmx : typing/types.cmx typing/typedtreeMap.cmx \
     typing/typedtree.cmx utils/misc.cmx parsing/location.cmx \
     parsing/lexer.cmx typing/env.cmx utils/config.cmx typing/cmi_format.cmx \
     utils/clflags.cmx typing/cmt_format.cmi
-typing/ctype.cmo : typing/types.cmi typing/subst.cmi typing/path.cmi \
-    utils/misc.cmi parsing/longident.cmi parsing/location.cmi \
+typing/ctype.cmo : typing/types.cmi typing/subst.cmi typing/predef.cmi \
+    typing/path.cmi utils/misc.cmi parsing/longident.cmi parsing/location.cmi \
     typing/ident.cmi typing/env.cmi utils/clflags.cmi typing/btype.cmi \
     parsing/asttypes.cmi typing/ctype.cmi
-typing/ctype.cmx : typing/types.cmx typing/subst.cmx typing/path.cmx \
-    utils/misc.cmx parsing/longident.cmx parsing/location.cmx \
+typing/ctype.cmx : typing/types.cmx typing/subst.cmx typing/predef.cmx \
+    typing/path.cmx utils/misc.cmx parsing/longident.cmx parsing/location.cmx \
     typing/ident.cmx typing/env.cmx utils/clflags.cmx typing/btype.cmx \
     parsing/asttypes.cmi typing/ctype.cmi
 typing/datarepr.cmo : typing/types.cmi typing/predef.cmi typing/path.cmi \
@@ -448,10 +444,8 @@ bytecomp/bytepackager.cmx : typing/typemod.cmx bytecomp/translmod.cmx \
     typing/env.cmx bytecomp/emitcode.cmx utils/config.cmx \
     bytecomp/cmo_format.cmi utils/clflags.cmx bytecomp/bytelink.cmx \
     bytecomp/bytegen.cmx bytecomp/bytepackager.cmi
-bytecomp/bytesections.cmo : utils/misc.cmi utils/config.cmi \
-    bytecomp/bytesections.cmi
-bytecomp/bytesections.cmx : utils/misc.cmx utils/config.cmx \
-    bytecomp/bytesections.cmi
+bytecomp/bytesections.cmo : utils/config.cmi bytecomp/bytesections.cmi
+bytecomp/bytesections.cmx : utils/config.cmx bytecomp/bytesections.cmi
 bytecomp/dll.cmo : utils/misc.cmi utils/config.cmi bytecomp/dll.cmi
 bytecomp/dll.cmx : utils/misc.cmx utils/config.cmx bytecomp/dll.cmi
 bytecomp/emitcode.cmo : bytecomp/translmod.cmi typing/primitive.cmi \
diff --git a/Changes b/Changes
index 9cd3a71030..e5646d4fac 100644
--- a/Changes
+++ b/Changes
@@ -8,6 +8,8 @@ Language features:
 - Generative functors
 - Module aliases
 * Alternative syntax for string literals {id|...|id} (can break comments)
+- Separation between read-only strings (type string) and read-write byte
+  sequences (type bytes). Activated by command-line option -safe-string.
 
 Build system for the OCaml distribution:
 - Use -bin-annot when building.
@@ -74,6 +76,7 @@ Runtime system:
   64-bit integer type.
 
 Standard library:
+* Added a new module: Bytes.
 - PR#4986: add List.sort_uniq and Set.of_list
 - PR#5935: a faster version of "raise" which does not maintain the backtrace
 - PR#6146: support "Unix.kill pid Sys.sigkill" under Windows
diff --git a/Makefile b/Makefile
index 877df08ef0..1d7ece63ed 100644
--- a/Makefile
+++ b/Makefile
@@ -17,7 +17,8 @@ include stdlib/StdlibModules
 
 CAMLC=boot/ocamlrun boot/ocamlc -nostdlib -I boot
 CAMLOPT=boot/ocamlrun ./ocamlopt -nostdlib -I stdlib -I otherlibs/dynlink
-COMPFLAGS=-strict-sequence -w +33..39+48 -warn-error A -bin-annot $(INCLUDES)
+COMPFLAGS=-strict-sequence -w +33..39+48 -warn-error A -bin-annot \
+          -safe-string $(INCLUDES)
 LINKFLAGS=
 
 CAMLYACC=boot/ocamlyacc
diff --git a/VERSION b/VERSION
index 7bcd56547a..93caac7ef7 100644
--- a/VERSION
+++ b/VERSION
@@ -1,4 +1,4 @@
-4.02.0+dev4-2014-04-03
+4.02.0+dev5-2014-04-29
 
 # The version string is the first line of this file.
 # It must be in the format described in stdlib/sys.mli
diff --git a/asmcomp/asmpackager.ml b/asmcomp/asmpackager.ml
index a8fcfe7896..63ed21c89d 100644
--- a/asmcomp/asmpackager.ml
+++ b/asmcomp/asmpackager.ml
@@ -161,7 +161,7 @@ let package_object_files ppf files targetcmx
 
 (* The entry point *)
 
-let package_files ppf files targetcmx =
+let package_files ppf initial_env files targetcmx =
   let files =
     List.map
       (fun f ->
@@ -177,7 +177,8 @@ let package_files ppf files targetcmx =
   (* Set the name of the current compunit *)
   Compilenv.reset ?packname:!Clflags.for_package targetname;
   try
-    let coercion = Typemod.package_units files targetcmi targetname in
+    let coercion =
+      Typemod.package_units initial_env files targetcmi targetname in
     package_object_files ppf files targetcmx targetobj targetname coercion
   with x ->
     remove_file targetcmx; remove_file targetobj;
diff --git a/asmcomp/asmpackager.mli b/asmcomp/asmpackager.mli
index 65272b7ed7..4d47f5c283 100644
--- a/asmcomp/asmpackager.mli
+++ b/asmcomp/asmpackager.mli
@@ -13,7 +13,7 @@
 (* "Package" a set of .cmx/.o files into one .cmx/.o file having the
    original compilation units as sub-modules. *)
 
-val package_files: Format.formatter -> string list -> string -> unit
+val package_files: Format.formatter -> Env.t -> string list -> string -> unit
 
 type error =
     Illegal_renaming of string * string * string
diff --git a/asmcomp/compilenv.ml b/asmcomp/compilenv.ml
index 49a846667d..c7bbdb531e 100644
--- a/asmcomp/compilenv.ml
+++ b/asmcomp/compilenv.ml
@@ -118,7 +118,7 @@ let symbol_in_current_unit name =
 let read_unit_info filename =
   let ic = open_in_bin filename in
   try
-    let buffer = input_bytes ic (String.length cmx_magic_number) in
+    let buffer = really_input_string ic (String.length cmx_magic_number) in
     if buffer <> cmx_magic_number then begin
       close_in ic;
       raise(Error(Not_a_unit_info filename))
@@ -133,7 +133,7 @@ let read_unit_info filename =
 
 let read_library_info filename =
   let ic = open_in_bin filename in
-  let buffer = input_bytes ic (String.length cmxa_magic_number) in
+  let buffer = really_input_string ic (String.length cmxa_magic_number) in
   if buffer <> cmxa_magic_number then
     raise(Error(Not_a_unit_info filename));
   let infos = (input_value ic : library_infos) in
diff --git a/asmrun/.depend b/asmrun/.depend
index bec9f0c076..5ddaa0d396 100644
--- a/asmrun/.depend
+++ b/asmrun/.depend
@@ -1,756 +1,756 @@
 alloc.o: alloc.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/custom.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/stacks.h \
- ../byterun/memory.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/custom.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/stacks.h \
+  ../byterun/memory.h
 array.o: array.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h
 backtrace.o: backtrace.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/backtrace.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/misc.h ../byterun/mlvalues.h stack.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/backtrace.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/misc.h ../byterun/mlvalues.h stack.h
 callback.o: callback.c ../byterun/callback.h ../byterun/mlvalues.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/misc.h ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/mlvalues.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/misc.h ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/mlvalues.h
 compact.o: compact.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/finalise.h ../byterun/roots.h \
- ../byterun/misc.h ../byterun/config.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/mlvalues.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/freelist.h \
- ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/major_gc.h \
- ../byterun/memory.h ../byterun/mlvalues.h ../byterun/roots.h \
- ../byterun/weak.h
+  ../byterun/../config/s.h ../byterun/finalise.h ../byterun/roots.h \
+  ../byterun/misc.h ../byterun/config.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/mlvalues.h ../byterun/major_gc.h \
+  ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/freelist.h \
+  ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/major_gc.h \
+  ../byterun/memory.h ../byterun/mlvalues.h ../byterun/roots.h \
+  ../byterun/weak.h
 compare.o: compare.c ../byterun/custom.h ../byterun/mlvalues.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/misc.h ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/misc.h ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h
 custom.o: custom.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/custom.h ../byterun/fail.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/mlvalues.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/custom.h ../byterun/fail.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/mlvalues.h
 debugger.o: debugger.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/config.h ../byterun/debugger.h \
- ../byterun/misc.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/config.h ../byterun/debugger.h \
+  ../byterun/misc.h
 dynlink.o: dynlink.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/mlvalues.h ../byterun/dynlink.h \
- ../byterun/fail.h ../byterun/mlvalues.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/misc.h ../byterun/osdeps.h \
- ../byterun/prims.h
+  ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
+  ../byterun/config.h ../byterun/mlvalues.h ../byterun/dynlink.h \
+  ../byterun/fail.h ../byterun/mlvalues.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/misc.h ../byterun/osdeps.h \
+  ../byterun/prims.h
 extern.o: extern.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/custom.h ../byterun/fail.h \
- ../byterun/gc.h ../byterun/intext.h ../byterun/io.h ../byterun/io.h \
- ../byterun/md5.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h ../byterun/reverse.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/custom.h ../byterun/fail.h \
+  ../byterun/gc.h ../byterun/intext.h ../byterun/io.h ../byterun/io.h \
+  ../byterun/md5.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h ../byterun/reverse.h
 fail.o: fail.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/fail.h ../byterun/io.h ../byterun/gc.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/printexc.h \
- ../byterun/signals.h stack.h ../byterun/roots.h ../byterun/memory.h \
- ../byterun/callback.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/fail.h ../byterun/io.h ../byterun/gc.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/printexc.h \
+  ../byterun/signals.h stack.h ../byterun/roots.h ../byterun/memory.h \
+  ../byterun/callback.h
 finalise.o: finalise.c ../byterun/callback.h ../byterun/mlvalues.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/misc.h ../byterun/fail.h ../byterun/mlvalues.h \
- ../byterun/roots.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/signals.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/misc.h ../byterun/fail.h ../byterun/mlvalues.h \
+  ../byterun/roots.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/signals.h
 floats.o: floats.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/fail.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/misc.h \
- ../byterun/reverse.h ../byterun/stacks.h ../byterun/memory.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/fail.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/misc.h \
+  ../byterun/reverse.h ../byterun/stacks.h ../byterun/memory.h
 freelist.o: freelist.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/freelist.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/mlvalues.h ../byterun/gc.h \
- ../byterun/gc_ctrl.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/major_gc.h ../byterun/misc.h ../byterun/mlvalues.h
+  ../byterun/../config/s.h ../byterun/freelist.h ../byterun/misc.h \
+  ../byterun/config.h ../byterun/mlvalues.h ../byterun/gc.h \
+  ../byterun/gc_ctrl.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/major_gc.h ../byterun/misc.h ../byterun/mlvalues.h
 gc_ctrl.o: gc_ctrl.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/compact.h ../byterun/custom.h \
- ../byterun/finalise.h ../byterun/roots.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/freelist.h ../byterun/gc.h \
- ../byterun/gc_ctrl.h ../byterun/major_gc.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h stack.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/compact.h ../byterun/custom.h \
+  ../byterun/finalise.h ../byterun/roots.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/freelist.h ../byterun/gc.h \
+  ../byterun/gc_ctrl.h ../byterun/major_gc.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h stack.h
 globroots.o: globroots.c ../byterun/memory.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/gc.h \
- ../byterun/mlvalues.h ../byterun/misc.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/misc.h \
- ../byterun/mlvalues.h ../byterun/roots.h ../byterun/memory.h \
- ../byterun/globroots.h ../byterun/roots.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/gc.h \
+  ../byterun/mlvalues.h ../byterun/misc.h ../byterun/major_gc.h \
+  ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/misc.h \
+  ../byterun/mlvalues.h ../byterun/roots.h ../byterun/memory.h \
+  ../byterun/globroots.h ../byterun/roots.h
 hash.o: hash.c ../byterun/mlvalues.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/misc.h \
- ../byterun/custom.h ../byterun/mlvalues.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/hash.h ../byterun/int64_native.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/misc.h \
+  ../byterun/custom.h ../byterun/mlvalues.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/hash.h ../byterun/int64_native.h
 intern.o: intern.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/callback.h ../byterun/custom.h \
- ../byterun/fail.h ../byterun/gc.h ../byterun/intext.h ../byterun/io.h \
- ../byterun/io.h ../byterun/md5.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/mlvalues.h ../byterun/misc.h ../byterun/reverse.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/callback.h ../byterun/custom.h \
+  ../byterun/fail.h ../byterun/gc.h ../byterun/intext.h ../byterun/io.h \
+  ../byterun/io.h ../byterun/md5.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/mlvalues.h ../byterun/misc.h ../byterun/reverse.h
 ints.o: ints.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/custom.h ../byterun/fail.h ../byterun/intext.h \
- ../byterun/io.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h ../byterun/int64_native.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/custom.h ../byterun/fail.h ../byterun/intext.h \
+  ../byterun/io.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h ../byterun/int64_native.h
 io.o: io.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/mlvalues.h ../byterun/custom.h \
- ../byterun/fail.h ../byterun/io.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h ../byterun/signals.h \
- ../byterun/sys.h
+  ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
+  ../byterun/config.h ../byterun/mlvalues.h ../byterun/custom.h \
+  ../byterun/fail.h ../byterun/io.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h ../byterun/signals.h \
+  ../byterun/sys.h
 lexing.o: lexing.c ../byterun/fail.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/mlvalues.h ../byterun/stacks.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/mlvalues.h ../byterun/stacks.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/freelist.h ../byterun/minor_gc.h
 main.o: main.c ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/misc.h ../byterun/sys.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/misc.h ../byterun/sys.h
 major_gc.o: major_gc.c ../byterun/compact.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/misc.h \
- ../byterun/custom.h ../byterun/mlvalues.h ../byterun/config.h \
- ../byterun/fail.h ../byterun/finalise.h ../byterun/roots.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/freelist.h \
- ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/major_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h ../byterun/roots.h \
- ../byterun/weak.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/misc.h \
+  ../byterun/custom.h ../byterun/mlvalues.h ../byterun/config.h \
+  ../byterun/fail.h ../byterun/finalise.h ../byterun/roots.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/freelist.h \
+  ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/major_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h ../byterun/roots.h \
+  ../byterun/weak.h
 md5.o: md5.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/fail.h ../byterun/md5.h ../byterun/io.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/io.h \
- ../byterun/reverse.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/fail.h ../byterun/md5.h ../byterun/io.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/io.h \
+  ../byterun/reverse.h
 memory.o: memory.c ../byterun/fail.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/freelist.h ../byterun/gc.h \
- ../byterun/gc_ctrl.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/minor_gc.h ../byterun/minor_gc.h ../byterun/misc.h \
- ../byterun/mlvalues.h ../byterun/signals.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/freelist.h ../byterun/gc.h \
+  ../byterun/gc_ctrl.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/minor_gc.h ../byterun/minor_gc.h ../byterun/misc.h \
+  ../byterun/mlvalues.h ../byterun/signals.h
 meta.o: meta.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/config.h ../byterun/fail.h ../byterun/fix_code.h \
- ../byterun/interp.h ../byterun/intext.h ../byterun/io.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/minor_gc.h \
- ../byterun/minor_gc.h ../byterun/misc.h ../byterun/mlvalues.h \
- ../byterun/prims.h ../byterun/stacks.h ../byterun/memory.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/config.h ../byterun/fail.h ../byterun/fix_code.h \
+  ../byterun/interp.h ../byterun/intext.h ../byterun/io.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/minor_gc.h \
+  ../byterun/minor_gc.h ../byterun/misc.h ../byterun/mlvalues.h \
+  ../byterun/prims.h ../byterun/stacks.h ../byterun/memory.h
 minor_gc.o: minor_gc.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/fail.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/mlvalues.h ../byterun/finalise.h \
- ../byterun/roots.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/major_gc.h \
- ../byterun/memory.h ../byterun/minor_gc.h ../byterun/misc.h \
- ../byterun/mlvalues.h ../byterun/roots.h ../byterun/signals.h \
- ../byterun/weak.h
+  ../byterun/../config/s.h ../byterun/fail.h ../byterun/misc.h \
+  ../byterun/config.h ../byterun/mlvalues.h ../byterun/finalise.h \
+  ../byterun/roots.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/major_gc.h \
+  ../byterun/memory.h ../byterun/minor_gc.h ../byterun/misc.h \
+  ../byterun/mlvalues.h ../byterun/roots.h ../byterun/signals.h \
+  ../byterun/weak.h
 misc.o: misc.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/mlvalues.h \
- ../byterun/misc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h
+  ../byterun/../config/s.h ../byterun/misc.h ../byterun/config.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/mlvalues.h \
+  ../byterun/misc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h
 natdynlink.o: natdynlink.c ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/misc.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/mlvalues.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h stack.h ../byterun/callback.h ../byterun/alloc.h \
- ../byterun/intext.h ../byterun/io.h ../byterun/osdeps.h \
- ../byterun/fail.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/misc.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/mlvalues.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h stack.h ../byterun/callback.h ../byterun/alloc.h \
+  ../byterun/intext.h ../byterun/io.h ../byterun/osdeps.h \
+  ../byterun/fail.h
 obj.o: obj.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/fail.h ../byterun/gc.h ../byterun/interp.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/minor_gc.h \
- ../byterun/minor_gc.h ../byterun/misc.h ../byterun/mlvalues.h \
- ../byterun/prims.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/fail.h ../byterun/gc.h ../byterun/interp.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/minor_gc.h \
+  ../byterun/minor_gc.h ../byterun/misc.h ../byterun/mlvalues.h \
+  ../byterun/prims.h
 parsing.o: parsing.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/mlvalues.h ../byterun/config.h \
- ../byterun/misc.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/mlvalues.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/alloc.h
+  ../byterun/../config/s.h ../byterun/mlvalues.h ../byterun/config.h \
+  ../byterun/misc.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/mlvalues.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/alloc.h
 printexc.o: printexc.c ../byterun/backtrace.h ../byterun/mlvalues.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/misc.h ../byterun/callback.h ../byterun/debugger.h \
- ../byterun/fail.h ../byterun/misc.h ../byterun/mlvalues.h \
- ../byterun/printexc.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/misc.h ../byterun/callback.h ../byterun/debugger.h \
+  ../byterun/fail.h ../byterun/misc.h ../byterun/mlvalues.h \
+  ../byterun/printexc.h
 roots.o: roots.c ../byterun/finalise.h ../byterun/roots.h \
- ../byterun/misc.h ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/mlvalues.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/globroots.h ../byterun/memory.h \
- ../byterun/major_gc.h ../byterun/minor_gc.h ../byterun/misc.h \
- ../byterun/mlvalues.h stack.h ../byterun/roots.h
+  ../byterun/misc.h ../byterun/config.h ../byterun/../config/m.h \
+  ../byterun/../config/s.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/mlvalues.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/globroots.h ../byterun/memory.h \
+  ../byterun/major_gc.h ../byterun/minor_gc.h ../byterun/misc.h \
+  ../byterun/mlvalues.h stack.h ../byterun/roots.h
 signals.o: signals.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/callback.h ../byterun/config.h \
- ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h ../byterun/roots.h \
- ../byterun/memory.h ../byterun/signals.h ../byterun/signals_machdep.h \
- ../byterun/sys.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/callback.h ../byterun/config.h \
+  ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h ../byterun/roots.h \
+  ../byterun/memory.h ../byterun/signals.h ../byterun/signals_machdep.h \
+  ../byterun/sys.h
 signals_asm.o: signals_asm.c ../byterun/fail.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/osdeps.h ../byterun/signals.h ../byterun/signals_machdep.h \
- signals_osdep.h stack.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/osdeps.h ../byterun/signals.h ../byterun/signals_machdep.h \
+  signals_osdep.h stack.h
 startup.o: startup.c ../byterun/callback.h ../byterun/mlvalues.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/misc.h ../byterun/backtrace.h ../byterun/custom.h \
- ../byterun/debugger.h ../byterun/fail.h ../byterun/freelist.h \
- ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/intext.h ../byterun/io.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/misc.h \
- ../byterun/mlvalues.h ../byterun/osdeps.h ../byterun/printexc.h stack.h \
- ../byterun/sys.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/misc.h ../byterun/backtrace.h ../byterun/custom.h \
+  ../byterun/debugger.h ../byterun/fail.h ../byterun/freelist.h \
+  ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/intext.h \
+  ../byterun/io.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h ../byterun/osdeps.h \
+  ../byterun/printexc.h stack.h ../byterun/sys.h
 str.o: str.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/fail.h ../byterun/mlvalues.h ../byterun/misc.h \
- ../byterun/int64_native.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/fail.h ../byterun/mlvalues.h ../byterun/misc.h \
+  ../byterun/int64_native.h
 sys.o: sys.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/mlvalues.h ../byterun/debugger.h \
- ../byterun/fail.h ../byterun/instruct.h ../byterun/mlvalues.h \
- ../byterun/osdeps.h ../byterun/signals.h ../byterun/stacks.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/sys.h
+  ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
+  ../byterun/config.h ../byterun/mlvalues.h ../byterun/debugger.h \
+  ../byterun/fail.h ../byterun/instruct.h ../byterun/mlvalues.h \
+  ../byterun/osdeps.h ../byterun/signals.h ../byterun/stacks.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/sys.h
 terminfo.o: terminfo.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/mlvalues.h ../byterun/fail.h \
- ../byterun/io.h ../byterun/mlvalues.h
+  ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
+  ../byterun/config.h ../byterun/mlvalues.h ../byterun/fail.h \
+  ../byterun/io.h ../byterun/mlvalues.h
 unix.o: unix.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/memory.h ../byterun/config.h \
- ../byterun/gc.h ../byterun/mlvalues.h ../byterun/misc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/osdeps.h
+  ../byterun/../config/s.h ../byterun/memory.h ../byterun/config.h \
+  ../byterun/gc.h ../byterun/mlvalues.h ../byterun/misc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/osdeps.h
 weak.o: weak.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/fail.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/minor_gc.h ../byterun/mlvalues.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/fail.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/minor_gc.h ../byterun/mlvalues.h
 alloc.d.o: alloc.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/custom.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/stacks.h \
- ../byterun/memory.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/custom.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/stacks.h \
+  ../byterun/memory.h
 array.d.o: array.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h
 backtrace.d.o: backtrace.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/backtrace.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/misc.h ../byterun/mlvalues.h stack.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/backtrace.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/misc.h ../byterun/mlvalues.h stack.h
 callback.d.o: callback.c ../byterun/callback.h ../byterun/mlvalues.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/misc.h ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/mlvalues.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/misc.h ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/mlvalues.h
 compact.d.o: compact.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/finalise.h ../byterun/roots.h \
- ../byterun/misc.h ../byterun/config.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/mlvalues.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/freelist.h \
- ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/major_gc.h \
- ../byterun/memory.h ../byterun/mlvalues.h ../byterun/roots.h \
- ../byterun/weak.h
+  ../byterun/../config/s.h ../byterun/finalise.h ../byterun/roots.h \
+  ../byterun/misc.h ../byterun/config.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/mlvalues.h ../byterun/major_gc.h \
+  ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/freelist.h \
+  ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/major_gc.h \
+  ../byterun/memory.h ../byterun/mlvalues.h ../byterun/roots.h \
+  ../byterun/weak.h
 compare.d.o: compare.c ../byterun/custom.h ../byterun/mlvalues.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/misc.h ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/misc.h ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h
 custom.d.o: custom.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/custom.h ../byterun/fail.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/mlvalues.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/custom.h ../byterun/fail.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/mlvalues.h
 debugger.d.o: debugger.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/config.h ../byterun/debugger.h \
- ../byterun/misc.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/config.h ../byterun/debugger.h \
+  ../byterun/misc.h
 dynlink.d.o: dynlink.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/mlvalues.h ../byterun/dynlink.h \
- ../byterun/fail.h ../byterun/mlvalues.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/misc.h ../byterun/osdeps.h \
- ../byterun/prims.h
+  ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
+  ../byterun/config.h ../byterun/mlvalues.h ../byterun/dynlink.h \
+  ../byterun/fail.h ../byterun/mlvalues.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/misc.h ../byterun/osdeps.h \
+  ../byterun/prims.h
 extern.d.o: extern.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/custom.h ../byterun/fail.h \
- ../byterun/gc.h ../byterun/intext.h ../byterun/io.h ../byterun/io.h \
- ../byterun/md5.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h ../byterun/reverse.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/custom.h ../byterun/fail.h \
+  ../byterun/gc.h ../byterun/intext.h ../byterun/io.h ../byterun/io.h \
+  ../byterun/md5.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h ../byterun/reverse.h
 fail.d.o: fail.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/fail.h ../byterun/io.h ../byterun/gc.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/printexc.h \
- ../byterun/signals.h stack.h ../byterun/roots.h ../byterun/memory.h \
- ../byterun/callback.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/fail.h ../byterun/io.h ../byterun/gc.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/printexc.h \
+  ../byterun/signals.h stack.h ../byterun/roots.h ../byterun/memory.h \
+  ../byterun/callback.h
 finalise.d.o: finalise.c ../byterun/callback.h ../byterun/mlvalues.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/misc.h ../byterun/fail.h ../byterun/mlvalues.h \
- ../byterun/roots.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/signals.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/misc.h ../byterun/fail.h ../byterun/mlvalues.h \
+  ../byterun/roots.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/signals.h
 floats.d.o: floats.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/fail.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/misc.h \
- ../byterun/reverse.h ../byterun/stacks.h ../byterun/memory.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/fail.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/misc.h \
+  ../byterun/reverse.h ../byterun/stacks.h ../byterun/memory.h
 freelist.d.o: freelist.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/freelist.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/mlvalues.h ../byterun/gc.h \
- ../byterun/gc_ctrl.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/major_gc.h ../byterun/misc.h ../byterun/mlvalues.h
+  ../byterun/../config/s.h ../byterun/freelist.h ../byterun/misc.h \
+  ../byterun/config.h ../byterun/mlvalues.h ../byterun/gc.h \
+  ../byterun/gc_ctrl.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/major_gc.h ../byterun/misc.h ../byterun/mlvalues.h
 gc_ctrl.d.o: gc_ctrl.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/compact.h ../byterun/custom.h \
- ../byterun/finalise.h ../byterun/roots.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/freelist.h ../byterun/gc.h \
- ../byterun/gc_ctrl.h ../byterun/major_gc.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h stack.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/compact.h ../byterun/custom.h \
+  ../byterun/finalise.h ../byterun/roots.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/freelist.h ../byterun/gc.h \
+  ../byterun/gc_ctrl.h ../byterun/major_gc.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h stack.h
 globroots.d.o: globroots.c ../byterun/memory.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/gc.h \
- ../byterun/mlvalues.h ../byterun/misc.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/misc.h \
- ../byterun/mlvalues.h ../byterun/roots.h ../byterun/memory.h \
- ../byterun/globroots.h ../byterun/roots.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/gc.h \
+  ../byterun/mlvalues.h ../byterun/misc.h ../byterun/major_gc.h \
+  ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/misc.h \
+  ../byterun/mlvalues.h ../byterun/roots.h ../byterun/memory.h \
+  ../byterun/globroots.h ../byterun/roots.h
 hash.d.o: hash.c ../byterun/mlvalues.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/misc.h \
- ../byterun/custom.h ../byterun/mlvalues.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/hash.h ../byterun/int64_native.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/misc.h \
+  ../byterun/custom.h ../byterun/mlvalues.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/hash.h ../byterun/int64_native.h
 intern.d.o: intern.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/callback.h ../byterun/custom.h \
- ../byterun/fail.h ../byterun/gc.h ../byterun/intext.h ../byterun/io.h \
- ../byterun/io.h ../byterun/md5.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/mlvalues.h ../byterun/misc.h ../byterun/reverse.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/callback.h ../byterun/custom.h \
+  ../byterun/fail.h ../byterun/gc.h ../byterun/intext.h ../byterun/io.h \
+  ../byterun/io.h ../byterun/md5.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/mlvalues.h ../byterun/misc.h ../byterun/reverse.h
 ints.d.o: ints.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/custom.h ../byterun/fail.h ../byterun/intext.h \
- ../byterun/io.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h ../byterun/int64_native.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/custom.h ../byterun/fail.h ../byterun/intext.h \
+  ../byterun/io.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h ../byterun/int64_native.h
 io.d.o: io.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/mlvalues.h ../byterun/custom.h \
- ../byterun/fail.h ../byterun/io.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h ../byterun/signals.h \
- ../byterun/sys.h
+  ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
+  ../byterun/config.h ../byterun/mlvalues.h ../byterun/custom.h \
+  ../byterun/fail.h ../byterun/io.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h ../byterun/signals.h \
+  ../byterun/sys.h
 lexing.d.o: lexing.c ../byterun/fail.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/mlvalues.h ../byterun/stacks.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/mlvalues.h ../byterun/stacks.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/freelist.h ../byterun/minor_gc.h
 main.d.o: main.c ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/misc.h ../byterun/sys.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/misc.h ../byterun/sys.h
 major_gc.d.o: major_gc.c ../byterun/compact.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/misc.h \
- ../byterun/custom.h ../byterun/mlvalues.h ../byterun/config.h \
- ../byterun/fail.h ../byterun/finalise.h ../byterun/roots.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/freelist.h \
- ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/major_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h ../byterun/roots.h \
- ../byterun/weak.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/misc.h \
+  ../byterun/custom.h ../byterun/mlvalues.h ../byterun/config.h \
+  ../byterun/fail.h ../byterun/finalise.h ../byterun/roots.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/freelist.h \
+  ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/major_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h ../byterun/roots.h \
+  ../byterun/weak.h
 md5.d.o: md5.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/fail.h ../byterun/md5.h ../byterun/io.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/io.h \
- ../byterun/reverse.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/fail.h ../byterun/md5.h ../byterun/io.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/io.h \
+  ../byterun/reverse.h
 memory.d.o: memory.c ../byterun/fail.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/freelist.h ../byterun/gc.h \
- ../byterun/gc_ctrl.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/minor_gc.h ../byterun/minor_gc.h ../byterun/misc.h \
- ../byterun/mlvalues.h ../byterun/signals.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/freelist.h ../byterun/gc.h \
+  ../byterun/gc_ctrl.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/minor_gc.h ../byterun/minor_gc.h ../byterun/misc.h \
+  ../byterun/mlvalues.h ../byterun/signals.h
 meta.d.o: meta.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/config.h ../byterun/fail.h ../byterun/fix_code.h \
- ../byterun/interp.h ../byterun/intext.h ../byterun/io.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/minor_gc.h \
- ../byterun/minor_gc.h ../byterun/misc.h ../byterun/mlvalues.h \
- ../byterun/prims.h ../byterun/stacks.h ../byterun/memory.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/config.h ../byterun/fail.h ../byterun/fix_code.h \
+  ../byterun/interp.h ../byterun/intext.h ../byterun/io.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/minor_gc.h \
+  ../byterun/minor_gc.h ../byterun/misc.h ../byterun/mlvalues.h \
+  ../byterun/prims.h ../byterun/stacks.h ../byterun/memory.h
 minor_gc.d.o: minor_gc.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/fail.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/mlvalues.h ../byterun/finalise.h \
- ../byterun/roots.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/major_gc.h \
- ../byterun/memory.h ../byterun/minor_gc.h ../byterun/misc.h \
- ../byterun/mlvalues.h ../byterun/roots.h ../byterun/signals.h \
- ../byterun/weak.h
+  ../byterun/../config/s.h ../byterun/fail.h ../byterun/misc.h \
+  ../byterun/config.h ../byterun/mlvalues.h ../byterun/finalise.h \
+  ../byterun/roots.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/major_gc.h \
+  ../byterun/memory.h ../byterun/minor_gc.h ../byterun/misc.h \
+  ../byterun/mlvalues.h ../byterun/roots.h ../byterun/signals.h \
+  ../byterun/weak.h
 misc.d.o: misc.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/mlvalues.h \
- ../byterun/misc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h
+  ../byterun/../config/s.h ../byterun/misc.h ../byterun/config.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/mlvalues.h \
+  ../byterun/misc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h
 natdynlink.d.o: natdynlink.c ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/misc.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/mlvalues.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h stack.h ../byterun/callback.h ../byterun/alloc.h \
- ../byterun/intext.h ../byterun/io.h ../byterun/osdeps.h \
- ../byterun/fail.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/misc.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/mlvalues.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h stack.h ../byterun/callback.h ../byterun/alloc.h \
+  ../byterun/intext.h ../byterun/io.h ../byterun/osdeps.h \
+  ../byterun/fail.h
 obj.d.o: obj.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/fail.h ../byterun/gc.h ../byterun/interp.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/minor_gc.h \
- ../byterun/minor_gc.h ../byterun/misc.h ../byterun/mlvalues.h \
- ../byterun/prims.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/fail.h ../byterun/gc.h ../byterun/interp.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/minor_gc.h \
+  ../byterun/minor_gc.h ../byterun/misc.h ../byterun/mlvalues.h \
+  ../byterun/prims.h
 parsing.d.o: parsing.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/mlvalues.h ../byterun/config.h \
- ../byterun/misc.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/mlvalues.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/alloc.h
+  ../byterun/../config/s.h ../byterun/mlvalues.h ../byterun/config.h \
+  ../byterun/misc.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/mlvalues.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/alloc.h
 printexc.d.o: printexc.c ../byterun/backtrace.h ../byterun/mlvalues.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/misc.h ../byterun/callback.h ../byterun/debugger.h \
- ../byterun/fail.h ../byterun/misc.h ../byterun/mlvalues.h \
- ../byterun/printexc.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/misc.h ../byterun/callback.h ../byterun/debugger.h \
+  ../byterun/fail.h ../byterun/misc.h ../byterun/mlvalues.h \
+  ../byterun/printexc.h
 roots.d.o: roots.c ../byterun/finalise.h ../byterun/roots.h \
- ../byterun/misc.h ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/mlvalues.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/globroots.h ../byterun/memory.h \
- ../byterun/major_gc.h ../byterun/minor_gc.h ../byterun/misc.h \
- ../byterun/mlvalues.h stack.h ../byterun/roots.h
+  ../byterun/misc.h ../byterun/config.h ../byterun/../config/m.h \
+  ../byterun/../config/s.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/mlvalues.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/globroots.h ../byterun/memory.h \
+  ../byterun/major_gc.h ../byterun/minor_gc.h ../byterun/misc.h \
+  ../byterun/mlvalues.h stack.h ../byterun/roots.h
 signals.d.o: signals.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/callback.h ../byterun/config.h \
- ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h ../byterun/roots.h \
- ../byterun/memory.h ../byterun/signals.h ../byterun/signals_machdep.h \
- ../byterun/sys.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/callback.h ../byterun/config.h \
+  ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h ../byterun/roots.h \
+  ../byterun/memory.h ../byterun/signals.h ../byterun/signals_machdep.h \
+  ../byterun/sys.h
 signals_asm.d.o: signals_asm.c ../byterun/fail.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/osdeps.h ../byterun/signals.h ../byterun/signals_machdep.h \
- signals_osdep.h stack.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/osdeps.h ../byterun/signals.h ../byterun/signals_machdep.h \
+  signals_osdep.h stack.h
 startup.d.o: startup.c ../byterun/callback.h ../byterun/mlvalues.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/misc.h ../byterun/backtrace.h ../byterun/custom.h \
- ../byterun/debugger.h ../byterun/fail.h ../byterun/freelist.h \
- ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/intext.h ../byterun/io.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/misc.h \
- ../byterun/mlvalues.h ../byterun/osdeps.h ../byterun/printexc.h stack.h \
- ../byterun/sys.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/misc.h ../byterun/backtrace.h ../byterun/custom.h \
+  ../byterun/debugger.h ../byterun/fail.h ../byterun/freelist.h \
+  ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/intext.h \
+  ../byterun/io.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h ../byterun/osdeps.h \
+  ../byterun/printexc.h stack.h ../byterun/sys.h
 str.d.o: str.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/fail.h ../byterun/mlvalues.h ../byterun/misc.h \
- ../byterun/int64_native.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/fail.h ../byterun/mlvalues.h ../byterun/misc.h \
+  ../byterun/int64_native.h
 sys.d.o: sys.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/mlvalues.h ../byterun/debugger.h \
- ../byterun/fail.h ../byterun/instruct.h ../byterun/mlvalues.h \
- ../byterun/osdeps.h ../byterun/signals.h ../byterun/stacks.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/sys.h
+  ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
+  ../byterun/config.h ../byterun/mlvalues.h ../byterun/debugger.h \
+  ../byterun/fail.h ../byterun/instruct.h ../byterun/mlvalues.h \
+  ../byterun/osdeps.h ../byterun/signals.h ../byterun/stacks.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/sys.h
 terminfo.d.o: terminfo.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/mlvalues.h ../byterun/fail.h \
- ../byterun/io.h ../byterun/mlvalues.h
+  ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
+  ../byterun/config.h ../byterun/mlvalues.h ../byterun/fail.h \
+  ../byterun/io.h ../byterun/mlvalues.h
 unix.d.o: unix.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/memory.h ../byterun/config.h \
- ../byterun/gc.h ../byterun/mlvalues.h ../byterun/misc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/osdeps.h
+  ../byterun/../config/s.h ../byterun/memory.h ../byterun/config.h \
+  ../byterun/gc.h ../byterun/mlvalues.h ../byterun/misc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/osdeps.h
 weak.d.o: weak.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/fail.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/minor_gc.h ../byterun/mlvalues.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/fail.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/minor_gc.h ../byterun/mlvalues.h
 alloc.p.o: alloc.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/custom.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/stacks.h \
- ../byterun/memory.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/custom.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/stacks.h \
+  ../byterun/memory.h
 array.p.o: array.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h
 backtrace.p.o: backtrace.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/backtrace.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/misc.h ../byterun/mlvalues.h stack.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/backtrace.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/misc.h ../byterun/mlvalues.h stack.h
 callback.p.o: callback.c ../byterun/callback.h ../byterun/mlvalues.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/misc.h ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/mlvalues.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/misc.h ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/mlvalues.h
 compact.p.o: compact.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/finalise.h ../byterun/roots.h \
- ../byterun/misc.h ../byterun/config.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/mlvalues.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/freelist.h \
- ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/major_gc.h \
- ../byterun/memory.h ../byterun/mlvalues.h ../byterun/roots.h \
- ../byterun/weak.h
+  ../byterun/../config/s.h ../byterun/finalise.h ../byterun/roots.h \
+  ../byterun/misc.h ../byterun/config.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/mlvalues.h ../byterun/major_gc.h \
+  ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/freelist.h \
+  ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/major_gc.h \
+  ../byterun/memory.h ../byterun/mlvalues.h ../byterun/roots.h \
+  ../byterun/weak.h
 compare.p.o: compare.c ../byterun/custom.h ../byterun/mlvalues.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/misc.h ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/misc.h ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h
 custom.p.o: custom.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/custom.h ../byterun/fail.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/mlvalues.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/custom.h ../byterun/fail.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/mlvalues.h
 debugger.p.o: debugger.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/config.h ../byterun/debugger.h \
- ../byterun/misc.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/config.h ../byterun/debugger.h \
+  ../byterun/misc.h
 dynlink.p.o: dynlink.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/mlvalues.h ../byterun/dynlink.h \
- ../byterun/fail.h ../byterun/mlvalues.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/misc.h ../byterun/osdeps.h \
- ../byterun/prims.h
+  ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
+  ../byterun/config.h ../byterun/mlvalues.h ../byterun/dynlink.h \
+  ../byterun/fail.h ../byterun/mlvalues.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/misc.h ../byterun/osdeps.h \
+  ../byterun/prims.h
 extern.p.o: extern.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/custom.h ../byterun/fail.h \
- ../byterun/gc.h ../byterun/intext.h ../byterun/io.h ../byterun/io.h \
- ../byterun/md5.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h ../byterun/reverse.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/custom.h ../byterun/fail.h \
+  ../byterun/gc.h ../byterun/intext.h ../byterun/io.h ../byterun/io.h \
+  ../byterun/md5.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h ../byterun/reverse.h
 fail.p.o: fail.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/fail.h ../byterun/io.h ../byterun/gc.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/printexc.h \
- ../byterun/signals.h stack.h ../byterun/roots.h ../byterun/memory.h \
- ../byterun/callback.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/fail.h ../byterun/io.h ../byterun/gc.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/printexc.h \
+  ../byterun/signals.h stack.h ../byterun/roots.h ../byterun/memory.h \
+  ../byterun/callback.h
 finalise.p.o: finalise.c ../byterun/callback.h ../byterun/mlvalues.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/misc.h ../byterun/fail.h ../byterun/mlvalues.h \
- ../byterun/roots.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/signals.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/misc.h ../byterun/fail.h ../byterun/mlvalues.h \
+  ../byterun/roots.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/signals.h
 floats.p.o: floats.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/fail.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/misc.h \
- ../byterun/reverse.h ../byterun/stacks.h ../byterun/memory.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/fail.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/misc.h \
+  ../byterun/reverse.h ../byterun/stacks.h ../byterun/memory.h
 freelist.p.o: freelist.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/freelist.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/mlvalues.h ../byterun/gc.h \
- ../byterun/gc_ctrl.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/major_gc.h ../byterun/misc.h ../byterun/mlvalues.h
+  ../byterun/../config/s.h ../byterun/freelist.h ../byterun/misc.h \
+  ../byterun/config.h ../byterun/mlvalues.h ../byterun/gc.h \
+  ../byterun/gc_ctrl.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/major_gc.h ../byterun/misc.h ../byterun/mlvalues.h
 gc_ctrl.p.o: gc_ctrl.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/compact.h ../byterun/custom.h \
- ../byterun/finalise.h ../byterun/roots.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/freelist.h ../byterun/gc.h \
- ../byterun/gc_ctrl.h ../byterun/major_gc.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h stack.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/compact.h ../byterun/custom.h \
+  ../byterun/finalise.h ../byterun/roots.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/freelist.h ../byterun/gc.h \
+  ../byterun/gc_ctrl.h ../byterun/major_gc.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h stack.h
 globroots.p.o: globroots.c ../byterun/memory.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/gc.h \
- ../byterun/mlvalues.h ../byterun/misc.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/misc.h \
- ../byterun/mlvalues.h ../byterun/roots.h ../byterun/memory.h \
- ../byterun/globroots.h ../byterun/roots.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/gc.h \
+  ../byterun/mlvalues.h ../byterun/misc.h ../byterun/major_gc.h \
+  ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/misc.h \
+  ../byterun/mlvalues.h ../byterun/roots.h ../byterun/memory.h \
+  ../byterun/globroots.h ../byterun/roots.h
 hash.p.o: hash.c ../byterun/mlvalues.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/misc.h \
- ../byterun/custom.h ../byterun/mlvalues.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/hash.h ../byterun/int64_native.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/misc.h \
+  ../byterun/custom.h ../byterun/mlvalues.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/hash.h ../byterun/int64_native.h
 intern.p.o: intern.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/callback.h ../byterun/custom.h \
- ../byterun/fail.h ../byterun/gc.h ../byterun/intext.h ../byterun/io.h \
- ../byterun/io.h ../byterun/md5.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/mlvalues.h ../byterun/misc.h ../byterun/reverse.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/callback.h ../byterun/custom.h \
+  ../byterun/fail.h ../byterun/gc.h ../byterun/intext.h ../byterun/io.h \
+  ../byterun/io.h ../byterun/md5.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/mlvalues.h ../byterun/misc.h ../byterun/reverse.h
 ints.p.o: ints.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/custom.h ../byterun/fail.h ../byterun/intext.h \
- ../byterun/io.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h ../byterun/int64_native.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/custom.h ../byterun/fail.h ../byterun/intext.h \
+  ../byterun/io.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h ../byterun/int64_native.h
 io.p.o: io.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/mlvalues.h ../byterun/custom.h \
- ../byterun/fail.h ../byterun/io.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h ../byterun/signals.h \
- ../byterun/sys.h
+  ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
+  ../byterun/config.h ../byterun/mlvalues.h ../byterun/custom.h \
+  ../byterun/fail.h ../byterun/io.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h ../byterun/signals.h \
+  ../byterun/sys.h
 lexing.p.o: lexing.c ../byterun/fail.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/mlvalues.h ../byterun/stacks.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/mlvalues.h ../byterun/stacks.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/freelist.h ../byterun/minor_gc.h
 main.p.o: main.c ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/misc.h ../byterun/sys.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/misc.h ../byterun/sys.h
 major_gc.p.o: major_gc.c ../byterun/compact.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/misc.h \
- ../byterun/custom.h ../byterun/mlvalues.h ../byterun/config.h \
- ../byterun/fail.h ../byterun/finalise.h ../byterun/roots.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/freelist.h \
- ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/major_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h ../byterun/roots.h \
- ../byterun/weak.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/misc.h \
+  ../byterun/custom.h ../byterun/mlvalues.h ../byterun/config.h \
+  ../byterun/fail.h ../byterun/finalise.h ../byterun/roots.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/freelist.h \
+  ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/major_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h ../byterun/roots.h \
+  ../byterun/weak.h
 md5.p.o: md5.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/fail.h ../byterun/md5.h ../byterun/io.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/io.h \
- ../byterun/reverse.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/fail.h ../byterun/md5.h ../byterun/io.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/mlvalues.h ../byterun/io.h \
+  ../byterun/reverse.h
 memory.p.o: memory.c ../byterun/fail.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/freelist.h ../byterun/gc.h \
- ../byterun/gc_ctrl.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/minor_gc.h ../byterun/minor_gc.h ../byterun/misc.h \
- ../byterun/mlvalues.h ../byterun/signals.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/freelist.h ../byterun/gc.h \
+  ../byterun/gc_ctrl.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/minor_gc.h ../byterun/minor_gc.h ../byterun/misc.h \
+  ../byterun/mlvalues.h ../byterun/signals.h
 meta.p.o: meta.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/config.h ../byterun/fail.h ../byterun/fix_code.h \
- ../byterun/interp.h ../byterun/intext.h ../byterun/io.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/minor_gc.h \
- ../byterun/minor_gc.h ../byterun/misc.h ../byterun/mlvalues.h \
- ../byterun/prims.h ../byterun/stacks.h ../byterun/memory.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/config.h ../byterun/fail.h ../byterun/fix_code.h \
+  ../byterun/interp.h ../byterun/intext.h ../byterun/io.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/minor_gc.h \
+  ../byterun/minor_gc.h ../byterun/misc.h ../byterun/mlvalues.h \
+  ../byterun/prims.h ../byterun/stacks.h ../byterun/memory.h
 minor_gc.p.o: minor_gc.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/fail.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/mlvalues.h ../byterun/finalise.h \
- ../byterun/roots.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/major_gc.h \
- ../byterun/memory.h ../byterun/minor_gc.h ../byterun/misc.h \
- ../byterun/mlvalues.h ../byterun/roots.h ../byterun/signals.h \
- ../byterun/weak.h
+  ../byterun/../config/s.h ../byterun/fail.h ../byterun/misc.h \
+  ../byterun/config.h ../byterun/mlvalues.h ../byterun/finalise.h \
+  ../byterun/roots.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/major_gc.h \
+  ../byterun/memory.h ../byterun/minor_gc.h ../byterun/misc.h \
+  ../byterun/mlvalues.h ../byterun/roots.h ../byterun/signals.h \
+  ../byterun/weak.h
 misc.p.o: misc.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/mlvalues.h \
- ../byterun/misc.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h
+  ../byterun/../config/s.h ../byterun/misc.h ../byterun/config.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/mlvalues.h \
+  ../byterun/misc.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h
 natdynlink.p.o: natdynlink.c ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/misc.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/mlvalues.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h stack.h ../byterun/callback.h ../byterun/alloc.h \
- ../byterun/intext.h ../byterun/io.h ../byterun/osdeps.h \
- ../byterun/fail.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/misc.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/mlvalues.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h stack.h ../byterun/callback.h ../byterun/alloc.h \
+  ../byterun/intext.h ../byterun/io.h ../byterun/osdeps.h \
+  ../byterun/fail.h
 obj.p.o: obj.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/fail.h ../byterun/gc.h ../byterun/interp.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/memory.h \
- ../byterun/gc.h ../byterun/major_gc.h ../byterun/minor_gc.h \
- ../byterun/minor_gc.h ../byterun/misc.h ../byterun/mlvalues.h \
- ../byterun/prims.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/fail.h ../byterun/gc.h ../byterun/interp.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/memory.h \
+  ../byterun/gc.h ../byterun/major_gc.h ../byterun/minor_gc.h \
+  ../byterun/minor_gc.h ../byterun/misc.h ../byterun/mlvalues.h \
+  ../byterun/prims.h
 parsing.p.o: parsing.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/mlvalues.h ../byterun/config.h \
- ../byterun/misc.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/mlvalues.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/alloc.h
+  ../byterun/../config/s.h ../byterun/mlvalues.h ../byterun/config.h \
+  ../byterun/misc.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/mlvalues.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/alloc.h
 printexc.p.o: printexc.c ../byterun/backtrace.h ../byterun/mlvalues.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/misc.h ../byterun/callback.h ../byterun/debugger.h \
- ../byterun/fail.h ../byterun/misc.h ../byterun/mlvalues.h \
- ../byterun/printexc.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/misc.h ../byterun/callback.h ../byterun/debugger.h \
+  ../byterun/fail.h ../byterun/misc.h ../byterun/mlvalues.h \
+  ../byterun/printexc.h
 roots.p.o: roots.c ../byterun/finalise.h ../byterun/roots.h \
- ../byterun/misc.h ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/mlvalues.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/minor_gc.h ../byterun/globroots.h ../byterun/memory.h \
- ../byterun/major_gc.h ../byterun/minor_gc.h ../byterun/misc.h \
- ../byterun/mlvalues.h stack.h ../byterun/roots.h
+  ../byterun/misc.h ../byterun/config.h ../byterun/../config/m.h \
+  ../byterun/../config/s.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/mlvalues.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/minor_gc.h ../byterun/globroots.h ../byterun/memory.h \
+  ../byterun/major_gc.h ../byterun/minor_gc.h ../byterun/misc.h \
+  ../byterun/mlvalues.h stack.h ../byterun/roots.h
 signals.p.o: signals.c ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/callback.h ../byterun/config.h \
- ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/mlvalues.h ../byterun/roots.h \
- ../byterun/memory.h ../byterun/signals.h ../byterun/signals_machdep.h \
- ../byterun/sys.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/callback.h ../byterun/config.h \
+  ../byterun/fail.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h ../byterun/roots.h \
+  ../byterun/memory.h ../byterun/signals.h ../byterun/signals_machdep.h \
+  ../byterun/sys.h
 signals_asm.p.o: signals_asm.c ../byterun/fail.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/mlvalues.h ../byterun/memory.h ../byterun/gc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/osdeps.h ../byterun/signals.h ../byterun/signals_machdep.h \
- signals_osdep.h stack.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/mlvalues.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/osdeps.h ../byterun/signals.h ../byterun/signals_machdep.h \
+  signals_osdep.h stack.h
 startup.p.o: startup.c ../byterun/callback.h ../byterun/mlvalues.h \
- ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
- ../byterun/misc.h ../byterun/backtrace.h ../byterun/custom.h \
- ../byterun/debugger.h ../byterun/fail.h ../byterun/freelist.h \
- ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/intext.h ../byterun/io.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/misc.h \
- ../byterun/mlvalues.h ../byterun/osdeps.h ../byterun/printexc.h stack.h \
- ../byterun/sys.h
+  ../byterun/config.h ../byterun/../config/m.h ../byterun/../config/s.h \
+  ../byterun/misc.h ../byterun/backtrace.h ../byterun/custom.h \
+  ../byterun/debugger.h ../byterun/fail.h ../byterun/freelist.h \
+  ../byterun/gc.h ../byterun/gc_ctrl.h ../byterun/intext.h \
+  ../byterun/io.h ../byterun/memory.h ../byterun/gc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/mlvalues.h ../byterun/osdeps.h \
+  ../byterun/printexc.h stack.h ../byterun/sys.h
 str.p.o: str.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/fail.h ../byterun/mlvalues.h ../byterun/misc.h \
- ../byterun/int64_native.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/fail.h ../byterun/mlvalues.h ../byterun/misc.h \
+  ../byterun/int64_native.h
 sys.p.o: sys.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/mlvalues.h ../byterun/debugger.h \
- ../byterun/fail.h ../byterun/instruct.h ../byterun/mlvalues.h \
- ../byterun/osdeps.h ../byterun/signals.h ../byterun/stacks.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/sys.h
+  ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
+  ../byterun/config.h ../byterun/mlvalues.h ../byterun/debugger.h \
+  ../byterun/fail.h ../byterun/instruct.h ../byterun/mlvalues.h \
+  ../byterun/osdeps.h ../byterun/signals.h ../byterun/stacks.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/freelist.h ../byterun/minor_gc.h ../byterun/sys.h
 terminfo.p.o: terminfo.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
- ../byterun/config.h ../byterun/mlvalues.h ../byterun/fail.h \
- ../byterun/io.h ../byterun/mlvalues.h
+  ../byterun/../config/s.h ../byterun/alloc.h ../byterun/misc.h \
+  ../byterun/config.h ../byterun/mlvalues.h ../byterun/fail.h \
+  ../byterun/io.h ../byterun/mlvalues.h
 unix.p.o: unix.c ../byterun/config.h ../byterun/../config/m.h \
- ../byterun/../config/s.h ../byterun/memory.h ../byterun/config.h \
- ../byterun/gc.h ../byterun/mlvalues.h ../byterun/misc.h \
- ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
- ../byterun/misc.h ../byterun/osdeps.h
+  ../byterun/../config/s.h ../byterun/memory.h ../byterun/config.h \
+  ../byterun/gc.h ../byterun/mlvalues.h ../byterun/misc.h \
+  ../byterun/major_gc.h ../byterun/freelist.h ../byterun/minor_gc.h \
+  ../byterun/misc.h ../byterun/osdeps.h
 weak.p.o: weak.c ../byterun/alloc.h ../byterun/misc.h ../byterun/config.h \
- ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
- ../byterun/fail.h ../byterun/major_gc.h ../byterun/freelist.h \
- ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
- ../byterun/minor_gc.h ../byterun/mlvalues.h
+  ../byterun/../config/m.h ../byterun/../config/s.h ../byterun/mlvalues.h \
+  ../byterun/fail.h ../byterun/major_gc.h ../byterun/freelist.h \
+  ../byterun/memory.h ../byterun/gc.h ../byterun/major_gc.h \
+  ../byterun/minor_gc.h ../byterun/mlvalues.h
diff --git a/boot/ocamlc b/boot/ocamlc
index fb53417dc2..54509de1da 100755
--- a/boot/ocamlc
+++ b/boot/ocamlc
diff --git a/boot/ocamldep b/boot/ocamldep
index 8f832f2eb4..6fe1ad368a 100755
--- a/boot/ocamldep
+++ b/boot/ocamldep
diff --git a/boot/ocamllex b/boot/ocamllex
index 82ede36d81..69fbe9ee6b 100755
--- a/boot/ocamllex
+++ b/boot/ocamllex
diff --git a/bytecomp/bytelibrarian.ml b/bytecomp/bytelibrarian.ml
index c63cf80ec2..3b88981e1c 100644
--- a/bytecomp/bytelibrarian.ml
+++ b/bytecomp/bytelibrarian.ml
@@ -60,7 +60,7 @@ let copy_object_file ppf oc name =
       raise(Error(File_not_found name)) in
   let ic = open_in_bin file_name in
   try
-    let buffer = input_bytes ic (String.length cmo_magic_number) in
+    let buffer = really_input_string ic (String.length cmo_magic_number) in
     if buffer = cmo_magic_number then begin
       let compunit_pos = input_binary_int ic in
       seek_in ic compunit_pos;
diff --git a/bytecomp/bytelink.ml b/bytecomp/bytelink.ml
index 75db3533c9..d3410fa1e2 100644
--- a/bytecomp/bytelink.ml
+++ b/bytecomp/bytelink.ml
@@ -113,7 +113,7 @@ let scan_file obj_name tolink =
       raise(Error(File_not_found obj_name)) in
   let ic = open_in_bin file_name in
   try
-    let buffer = input_bytes ic (String.length cmo_magic_number) in
+    let buffer = really_input_string ic (String.length cmo_magic_number) in
     if buffer = cmo_magic_number then begin
       (* This is a .cmo file. It must be linked in any case.
          Read the relocation information to see which modules it
@@ -256,7 +256,7 @@ let output_debug_info oc =
   List.iter
     (fun (ofs, evl) ->
       output_binary_int oc ofs;
-      Array.iter (output_string oc) evl)
+      Array.iter (output_bytes oc) evl)
     !debug_info;
   debug_info := []
 
@@ -317,7 +317,7 @@ let link_bytecode ppf tolink exec_name standalone =
       try Dll.open_dlls Dll.For_checking sharedobjs
       with Failure reason -> raise(Error(Cannot_open_dll reason))
     end;
-    let output_fun = output_string outchan
+    let output_fun = output_bytes outchan
     and currpos_fun () = pos_out outchan - start_code in
     List.iter (link_file ppf output_fun currpos_fun) tolink;
     if check_dlls then Dll.close_all_dlls();
@@ -371,12 +371,12 @@ let output_code_string_counter = ref 0
 
 let output_code_string outchan code =
   let pos = ref 0 in
-  let len = String.length code in
+  let len = Bytes.length code in
   while !pos < len do
-    let c1 = Char.code(code.[!pos]) in
-    let c2 = Char.code(code.[!pos + 1]) in
-    let c3 = Char.code(code.[!pos + 2]) in
-    let c4 = Char.code(code.[!pos + 3]) in
+    let c1 = Char.code(Bytes.get code !pos) in
+    let c2 = Char.code(Bytes.get code (!pos + 1)) in
+    let c3 = Char.code(Bytes.get code (!pos + 2)) in
+    let c4 = Char.code(Bytes.get code (!pos + 3)) in
     pos := !pos + 4;
     Printf.fprintf outchan "0x%02x%02x%02x%02x, " c4 c3 c2 c1;
     incr output_code_string_counter;
@@ -444,7 +444,7 @@ let link_bytecode_as_c ppf tolink outfile =
     let currpos = ref 0 in
     let output_fun code =
       output_code_string outchan code;
-      currpos := !currpos + String.length code
+      currpos := !currpos + Bytes.length code
     and currpos_fun () = !currpos in
     List.iter (link_file ppf output_fun currpos_fun) tolink;
     (* The final STOP instruction *)
diff --git a/bytecomp/bytepackager.ml b/bytecomp/bytepackager.ml
index 23582c1cb2..0ec05244bb 100644
--- a/bytecomp/bytepackager.ml
+++ b/bytecomp/bytepackager.ml
@@ -101,7 +101,9 @@ let read_member_info file = (
     if Filename.check_suffix file ".cmo" then begin
     let ic = open_in_bin file in
     try
-      let buffer = input_bytes ic (String.length Config.cmo_magic_number) in
+      let buffer =
+        really_input_string ic (String.length Config.cmo_magic_number)
+      in
       if buffer <> Config.cmo_magic_number then
         raise(Error(Not_an_object_file file));
       let compunit_pos = input_binary_int ic in
@@ -248,7 +250,7 @@ let package_object_files ppf files targetfile targetname coercion =
 
 (* The entry point *)
 
-let package_files ppf files targetfile =
+let package_files ppf initial_env files targetfile =
     let files =
     List.map
         (fun f ->
@@ -259,11 +261,12 @@ let package_files ppf files targetfile =
     let targetcmi = prefix ^ ".cmi" in
     let targetname = String.capitalize(Filename.basename prefix) in
     try
-      let coercion = Typemod.package_units files targetcmi targetname in
-    let ret = package_object_files ppf files targetfile targetname coercion in
-    ret
-  with x ->
-    remove_file targetfile; raise x
+      let coercion =
+        Typemod.package_units initial_env files targetcmi targetname in
+      let ret = package_object_files ppf files targetfile targetname coercion in
+      ret
+    with x ->
+      remove_file targetfile; raise x
 
 (* Error report *)
 
diff --git a/bytecomp/bytepackager.mli b/bytecomp/bytepackager.mli
index 04de0726a2..64e100f585 100644
--- a/bytecomp/bytepackager.mli
+++ b/bytecomp/bytepackager.mli
@@ -13,7 +13,7 @@
 (* "Package" a set of .cmo files into one .cmo file having the
    original compilation units as sub-modules. *)
 
-val package_files: Format.formatter -> string list -> string -> unit
+val package_files: Format.formatter -> Env.t -> string list -> string -> unit
 
 type error =
     Forward_reference of string * Ident.t
diff --git a/bytecomp/bytesections.ml b/bytecomp/bytesections.ml
index 5af3bc5237..15afdc0efd 100644
--- a/bytecomp/bytesections.ml
+++ b/bytecomp/bytesections.ml
@@ -46,12 +46,14 @@ let read_toc ic =
   let pos_trailer = in_channel_length ic - 16 in
   seek_in ic pos_trailer;
   let num_sections = input_binary_int ic in
-  let header = Misc.input_bytes ic (String.length Config.exec_magic_number) in
+  let header =
+    really_input_string ic (String.length Config.exec_magic_number)
+  in
   if header <> Config.exec_magic_number then raise Bad_magic_number;
   seek_in ic (pos_trailer - 8 * num_sections);
   section_table := [];
   for _i = 1 to num_sections do
-    let name = Misc.input_bytes ic 4 in
+    let name = really_input_string ic 4 in
     let len = input_binary_int ic in
     section_table := (name, len) :: !section_table
   done
@@ -77,7 +79,7 @@ let seek_section ic name =
 (* Return the contents of a section, as a string *)
 
 let read_section_string ic name =
-  Misc.input_bytes ic (seek_section ic name)
+  really_input_string ic (seek_section ic name)
 
 (* Return the contents of a section, as marshalled data *)
 
diff --git a/bytecomp/emitcode.ml b/bytecomp/emitcode.ml
index a56bf9175b..17c09f44c6 100644
--- a/bytecomp/emitcode.ml
+++ b/bytecomp/emitcode.ml
@@ -402,7 +402,7 @@ let to_memory init_code fun_code =
   emit init_code;
   emit fun_code;
   let code = Meta.static_alloc !out_position in
-  LongString.unsafe_blit_to_string !out_buffer 0 code 0 !out_position;
+  LongString.unsafe_blit_to_bytes !out_buffer 0 code 0 !out_position;
   let reloc = List.rev !reloc_info
   and code_size = !out_position in
   init();
diff --git a/bytecomp/emitcode.mli b/bytecomp/emitcode.mli
index 60d791434a..729a53764b 100644
--- a/bytecomp/emitcode.mli
+++ b/bytecomp/emitcode.mli
@@ -21,7 +21,7 @@ val to_file: out_channel -> string -> instruction list -> unit
              name of compilation unit implemented
              list of instructions to emit *)
 val to_memory: instruction list -> instruction list ->
-                    string * int * (reloc_info * int) list
+                    bytes * int * (reloc_info * int) list
         (* Arguments:
              initialization code (terminated by STOP)
              function code
diff --git a/bytecomp/matching.ml b/bytecomp/matching.ml
index c57518afb3..02233d0eca 100644
--- a/bytecomp/matching.ml
+++ b/bytecomp/matching.ml
@@ -1484,7 +1484,7 @@ let get_mod_field modname field =
   lazy (
     try
       let mod_ident = Ident.create_persistent modname in
-      let env = Env.open_pers_signature modname Env.initial in
+      let env = Env.open_pers_signature modname Env.initial_safe_string in
       let p = try
         match Env.lookup_value (Longident.Lident field) env with
         | (Path.Pdot(_,_,i), _) -> i
diff --git a/bytecomp/meta.ml b/bytecomp/meta.ml
index 35d8776666..f7711ff15e 100644
--- a/bytecomp/meta.ml
+++ b/bytecomp/meta.ml
@@ -12,13 +12,13 @@
 
 external global_data : unit -> Obj.t array = "caml_get_global_data"
 external realloc_global_data : int -> unit = "caml_realloc_global"
-external static_alloc : int -> string = "caml_static_alloc"
-external static_free : string -> unit = "caml_static_free"
-external static_resize : string -> int -> string = "caml_static_resize"
-external static_release_bytecode : string -> int -> unit
+external static_alloc : int -> bytes = "caml_static_alloc"
+external static_free : bytes -> unit = "caml_static_free"
+external static_resize : bytes -> int -> bytes = "caml_static_resize"
+external static_release_bytecode : bytes -> int -> unit
                                  = "caml_static_release_bytecode"
 type closure = unit -> Obj.t
-external reify_bytecode : string -> int -> closure = "caml_reify_bytecode"
+external reify_bytecode : bytes -> int -> closure = "caml_reify_bytecode"
 external invoke_traced_function : Obj.t -> Obj.t -> Obj.t -> Obj.t
                                 = "caml_invoke_traced_function"
 external get_section_table : unit -> (string * Obj.t) list
diff --git a/bytecomp/meta.mli b/bytecomp/meta.mli
index a8ef5272aa..cb3565dcc8 100644
--- a/bytecomp/meta.mli
+++ b/bytecomp/meta.mli
@@ -14,13 +14,13 @@
 
 external global_data : unit -> Obj.t array = "caml_get_global_data"
 external realloc_global_data : int -> unit = "caml_realloc_global"
-external static_alloc : int -> string = "caml_static_alloc"
-external static_free : string -> unit = "caml_static_free"
-external static_release_bytecode : string -> int -> unit
+external static_alloc : int -> bytes = "caml_static_alloc"
+external static_free : bytes -> unit = "caml_static_free"
+external static_release_bytecode : bytes -> int -> unit
                                  = "caml_static_release_bytecode"
-external static_resize : string -> int -> string = "caml_static_resize"
+external static_resize : bytes -> int -> bytes = "caml_static_resize"
 type closure = unit -> Obj.t
-external reify_bytecode : string -> int -> closure = "caml_reify_bytecode"
+external reify_bytecode : bytes -> int -> closure = "caml_reify_bytecode"
 external invoke_traced_function : Obj.t -> Obj.t -> Obj.t -> Obj.t
                                 = "caml_invoke_traced_function"
 external get_section_table : unit -> (string * Obj.t) list
diff --git a/bytecomp/symtable.ml b/bytecomp/symtable.ml
index baff51c486..788c0e69d3 100644
--- a/bytecomp/symtable.ml
+++ b/bytecomp/symtable.ml
@@ -198,7 +198,7 @@ let gen_patch_object str_set buff patchlist =
           gen_patch_int str_set buff pos (num_of_prim name))
     patchlist
 
-let patch_object = gen_patch_object String.unsafe_set
+let patch_object = gen_patch_object Bytes.unsafe_set
 let ls_patch_object = gen_patch_object LongString.set
 
 (* Translate structured constants *)
diff --git a/bytecomp/symtable.mli b/bytecomp/symtable.mli
index e3c33d2396..82df2cd8a7 100644
--- a/bytecomp/symtable.mli
+++ b/bytecomp/symtable.mli
@@ -17,7 +17,7 @@ open Cmo_format
 (* Functions for batch linking *)
 
 val init: unit -> unit
-val patch_object: string -> (reloc_info * int) list -> unit
+val patch_object: bytes -> (reloc_info * int) list -> unit
 val ls_patch_object: Misc.LongString.t -> (reloc_info * int) list -> unit
 val require_primitive: string -> unit
 val initial_global_table: unit -> Obj.t array
diff --git a/byterun/.depend b/byterun/.depend
index a68ab0904e..2f1780db9e 100644
--- a/byterun/.depend
+++ b/byterun/.depend
@@ -1,419 +1,422 @@
 alloc.o: alloc.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h custom.h major_gc.h freelist.h memory.h gc.h \
- minor_gc.h stacks.h
+  ../config/s.h mlvalues.h custom.h major_gc.h freelist.h memory.h gc.h \
+  minor_gc.h stacks.h
 array.o: array.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h memory.h gc.h major_gc.h freelist.h \
- minor_gc.h
+  ../config/s.h mlvalues.h fail.h memory.h gc.h major_gc.h freelist.h \
+  minor_gc.h
 backtrace.o: backtrace.c config.h ../config/m.h ../config/s.h \
- compatibility.h mlvalues.h misc.h alloc.h io.h instruct.h intext.h \
- exec.h fix_code.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
- startup.h stacks.h sys.h backtrace.h
+  compatibility.h mlvalues.h misc.h alloc.h io.h instruct.h intext.h \
+  exec.h fix_code.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
+  startup.h stacks.h sys.h backtrace.h
 callback.o: callback.c callback.h compatibility.h mlvalues.h config.h \
- ../config/m.h ../config/s.h misc.h fail.h memory.h gc.h major_gc.h \
- freelist.h minor_gc.h interp.h instruct.h fix_code.h stacks.h
+  ../config/m.h ../config/s.h misc.h fail.h memory.h gc.h major_gc.h \
+  freelist.h minor_gc.h interp.h instruct.h fix_code.h stacks.h
 compact.o: compact.c config.h ../config/m.h ../config/s.h compatibility.h \
- finalise.h roots.h misc.h memory.h gc.h mlvalues.h major_gc.h freelist.h \
- minor_gc.h gc_ctrl.h weak.h
+  finalise.h roots.h misc.h memory.h gc.h mlvalues.h major_gc.h \
+  freelist.h minor_gc.h gc_ctrl.h weak.h
 compare.o: compare.c custom.h compatibility.h mlvalues.h config.h \
- ../config/m.h ../config/s.h misc.h fail.h memory.h gc.h major_gc.h \
- freelist.h minor_gc.h
+  ../config/m.h ../config/s.h misc.h fail.h memory.h gc.h major_gc.h \
+  freelist.h minor_gc.h
 custom.o: custom.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h custom.h fail.h memory.h gc.h major_gc.h \
- freelist.h minor_gc.h
+  ../config/s.h mlvalues.h custom.h fail.h memory.h gc.h major_gc.h \
+  freelist.h minor_gc.h
 debugger.o: debugger.c alloc.h compatibility.h misc.h config.h \
- ../config/m.h ../config/s.h mlvalues.h debugger.h fail.h fix_code.h \
- instruct.h intext.h io.h stacks.h memory.h gc.h major_gc.h freelist.h \
- minor_gc.h sys.h
+  ../config/m.h ../config/s.h mlvalues.h debugger.h fail.h fix_code.h \
+  instruct.h intext.h io.h stacks.h memory.h gc.h major_gc.h freelist.h \
+  minor_gc.h sys.h
 dynlink.o: dynlink.c config.h ../config/m.h ../config/s.h compatibility.h \
- alloc.h misc.h mlvalues.h dynlink.h fail.h memory.h gc.h major_gc.h \
- freelist.h minor_gc.h osdeps.h prims.h
+  alloc.h misc.h mlvalues.h dynlink.h fail.h memory.h gc.h major_gc.h \
+  freelist.h minor_gc.h osdeps.h prims.h
 extern.o: extern.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h custom.h fail.h gc.h intext.h io.h md5.h \
- memory.h major_gc.h freelist.h minor_gc.h reverse.h
+  ../config/s.h mlvalues.h custom.h fail.h gc.h intext.h io.h md5.h \
+  memory.h major_gc.h freelist.h minor_gc.h reverse.h
 fail.o: fail.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h io.h gc.h memory.h major_gc.h freelist.h \
- minor_gc.h printexc.h signals.h stacks.h
+  ../config/s.h mlvalues.h fail.h io.h gc.h memory.h major_gc.h \
+  freelist.h minor_gc.h printexc.h signals.h stacks.h
 finalise.o: finalise.c callback.h compatibility.h mlvalues.h config.h \
- ../config/m.h ../config/s.h misc.h fail.h roots.h memory.h gc.h \
- major_gc.h freelist.h minor_gc.h signals.h
+  ../config/m.h ../config/s.h misc.h fail.h roots.h memory.h gc.h \
+  major_gc.h freelist.h minor_gc.h signals.h
 fix_code.o: fix_code.c config.h ../config/m.h ../config/s.h \
- compatibility.h debugger.h misc.h mlvalues.h fix_code.h instruct.h \
- intext.h io.h md5.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
- reverse.h
+  compatibility.h debugger.h misc.h mlvalues.h fix_code.h instruct.h \
+  intext.h io.h md5.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
+  reverse.h
 floats.o: floats.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h memory.h gc.h major_gc.h freelist.h \
- minor_gc.h reverse.h stacks.h
+  ../config/s.h mlvalues.h fail.h memory.h gc.h major_gc.h freelist.h \
+  minor_gc.h reverse.h stacks.h
 freelist.o: freelist.c config.h ../config/m.h ../config/s.h \
- compatibility.h freelist.h misc.h mlvalues.h gc.h gc_ctrl.h memory.h \
- major_gc.h minor_gc.h
+  compatibility.h freelist.h misc.h mlvalues.h gc.h gc_ctrl.h memory.h \
+  major_gc.h minor_gc.h
 gc_ctrl.o: gc_ctrl.c alloc.h compatibility.h misc.h config.h \
- ../config/m.h ../config/s.h mlvalues.h compact.h custom.h finalise.h \
- roots.h memory.h gc.h major_gc.h freelist.h minor_gc.h gc_ctrl.h \
- stacks.h
+  ../config/m.h ../config/s.h mlvalues.h compact.h custom.h finalise.h \
+  roots.h memory.h gc.h major_gc.h freelist.h minor_gc.h gc_ctrl.h \
+  stacks.h
 globroots.o: globroots.c memory.h compatibility.h config.h ../config/m.h \
- ../config/s.h gc.h mlvalues.h misc.h major_gc.h freelist.h minor_gc.h \
- roots.h globroots.h
+  ../config/s.h gc.h mlvalues.h misc.h major_gc.h freelist.h minor_gc.h \
+  roots.h globroots.h
 hash.o: hash.c mlvalues.h compatibility.h config.h ../config/m.h \
- ../config/s.h misc.h custom.h memory.h gc.h major_gc.h freelist.h \
- minor_gc.h hash.h int64_native.h
+  ../config/s.h misc.h custom.h memory.h gc.h major_gc.h freelist.h \
+  minor_gc.h hash.h int64_native.h
 instrtrace.o: instrtrace.c
 intern.o: intern.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h callback.h custom.h fail.h gc.h intext.h io.h \
- md5.h memory.h major_gc.h freelist.h minor_gc.h reverse.h
+  ../config/s.h mlvalues.h callback.h custom.h fail.h gc.h intext.h io.h \
+  md5.h memory.h major_gc.h freelist.h minor_gc.h reverse.h
 interp.o: interp.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h backtrace.h callback.h debugger.h fail.h \
- fix_code.h instrtrace.h instruct.h interp.h major_gc.h freelist.h \
- memory.h gc.h minor_gc.h prims.h signals.h stacks.h jumptbl.h
+  ../config/s.h mlvalues.h backtrace.h callback.h debugger.h fail.h \
+  fix_code.h instrtrace.h instruct.h interp.h major_gc.h freelist.h \
+  memory.h gc.h minor_gc.h prims.h signals.h stacks.h jumptbl.h
 ints.o: ints.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h custom.h fail.h intext.h io.h memory.h gc.h \
- major_gc.h freelist.h minor_gc.h int64_native.h
+  ../config/s.h mlvalues.h custom.h fail.h intext.h io.h memory.h gc.h \
+  major_gc.h freelist.h minor_gc.h int64_native.h
 io.o: io.c config.h ../config/m.h ../config/s.h compatibility.h alloc.h \
- misc.h mlvalues.h custom.h fail.h io.h memory.h gc.h major_gc.h \
- freelist.h minor_gc.h signals.h sys.h
+  misc.h mlvalues.h custom.h fail.h io.h memory.h gc.h major_gc.h \
+  freelist.h minor_gc.h signals.h sys.h
 lexing.o: lexing.c fail.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h stacks.h memory.h gc.h major_gc.h freelist.h \
- minor_gc.h
+  ../config/s.h mlvalues.h stacks.h memory.h gc.h major_gc.h freelist.h \
+  minor_gc.h
 main.o: main.c misc.h compatibility.h config.h ../config/m.h \
- ../config/s.h mlvalues.h sys.h
+  ../config/s.h mlvalues.h sys.h
 major_gc.o: major_gc.c compact.h config.h ../config/m.h ../config/s.h \
- compatibility.h misc.h custom.h mlvalues.h fail.h finalise.h roots.h \
- memory.h gc.h major_gc.h freelist.h minor_gc.h gc_ctrl.h weak.h
+  compatibility.h misc.h custom.h mlvalues.h fail.h finalise.h roots.h \
+  memory.h gc.h major_gc.h freelist.h minor_gc.h gc_ctrl.h weak.h
 md5.o: md5.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h md5.h io.h memory.h gc.h major_gc.h \
- freelist.h minor_gc.h reverse.h
+  ../config/s.h mlvalues.h fail.h md5.h io.h memory.h gc.h major_gc.h \
+  freelist.h minor_gc.h reverse.h
 memory.o: memory.c fail.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h freelist.h gc.h gc_ctrl.h major_gc.h memory.h \
- minor_gc.h signals.h
+  ../config/s.h mlvalues.h freelist.h gc.h gc_ctrl.h major_gc.h memory.h \
+  minor_gc.h signals.h
 meta.o: meta.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h fix_code.h interp.h intext.h io.h \
- major_gc.h freelist.h memory.h gc.h minor_gc.h prims.h stacks.h
+  ../config/s.h mlvalues.h fail.h fix_code.h interp.h intext.h io.h \
+  major_gc.h freelist.h memory.h gc.h minor_gc.h prims.h stacks.h
 minor_gc.o: minor_gc.c config.h ../config/m.h ../config/s.h \
- compatibility.h fail.h misc.h mlvalues.h finalise.h roots.h memory.h \
- gc.h major_gc.h freelist.h minor_gc.h gc_ctrl.h signals.h weak.h
+  compatibility.h fail.h misc.h mlvalues.h finalise.h roots.h memory.h \
+  gc.h major_gc.h freelist.h minor_gc.h gc_ctrl.h signals.h weak.h
 misc.o: misc.c config.h ../config/m.h ../config/s.h compatibility.h \
- misc.h memory.h gc.h mlvalues.h major_gc.h freelist.h minor_gc.h
+  misc.h memory.h gc.h mlvalues.h major_gc.h freelist.h minor_gc.h
 obj.o: obj.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h gc.h interp.h major_gc.h freelist.h \
- memory.h minor_gc.h prims.h
+  ../config/s.h mlvalues.h fail.h gc.h interp.h major_gc.h freelist.h \
+  memory.h minor_gc.h prims.h
 parsing.o: parsing.c config.h ../config/m.h ../config/s.h compatibility.h \
- mlvalues.h misc.h memory.h gc.h major_gc.h freelist.h minor_gc.h alloc.h
+  mlvalues.h misc.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
+  alloc.h
 prims.o: prims.c mlvalues.h compatibility.h config.h ../config/m.h \
- ../config/s.h misc.h prims.h
+  ../config/s.h misc.h prims.h
 printexc.o: printexc.c backtrace.h mlvalues.h compatibility.h config.h \
- ../config/m.h ../config/s.h misc.h callback.h debugger.h fail.h \
- printexc.h
+  ../config/m.h ../config/s.h misc.h callback.h debugger.h fail.h \
+  printexc.h
 roots.o: roots.c finalise.h roots.h misc.h compatibility.h config.h \
- ../config/m.h ../config/s.h memory.h gc.h mlvalues.h major_gc.h \
- freelist.h minor_gc.h globroots.h stacks.h
+  ../config/m.h ../config/s.h memory.h gc.h mlvalues.h major_gc.h \
+  freelist.h minor_gc.h globroots.h stacks.h
 signals.o: signals.c alloc.h compatibility.h misc.h config.h \
- ../config/m.h ../config/s.h mlvalues.h callback.h fail.h memory.h gc.h \
- major_gc.h freelist.h minor_gc.h roots.h signals.h signals_machdep.h \
- sys.h
+  ../config/m.h ../config/s.h mlvalues.h callback.h fail.h memory.h gc.h \
+  major_gc.h freelist.h minor_gc.h roots.h signals.h signals_machdep.h \
+  sys.h
 signals_byt.o: signals_byt.c config.h ../config/m.h ../config/s.h \
- compatibility.h memory.h gc.h mlvalues.h misc.h major_gc.h freelist.h \
- minor_gc.h osdeps.h signals.h signals_machdep.h
+  compatibility.h memory.h gc.h mlvalues.h misc.h major_gc.h freelist.h \
+  minor_gc.h osdeps.h signals.h signals_machdep.h
 stacks.o: stacks.c config.h ../config/m.h ../config/s.h compatibility.h \
- fail.h misc.h mlvalues.h stacks.h memory.h gc.h major_gc.h freelist.h \
- minor_gc.h
+  fail.h misc.h mlvalues.h stacks.h memory.h gc.h major_gc.h freelist.h \
+  minor_gc.h
 startup.o: startup.c config.h ../config/m.h ../config/s.h compatibility.h \
- alloc.h misc.h mlvalues.h backtrace.h callback.h custom.h debugger.h \
- dynlink.h exec.h fail.h fix_code.h freelist.h gc_ctrl.h instrtrace.h \
- interp.h intext.h io.h memory.h gc.h major_gc.h minor_gc.h osdeps.h \
- prims.h printexc.h reverse.h signals.h stacks.h sys.h startup.h \
- version.h
+  alloc.h misc.h mlvalues.h backtrace.h callback.h custom.h debugger.h \
+  dynlink.h exec.h fail.h fix_code.h freelist.h gc_ctrl.h instrtrace.h \
+  interp.h intext.h io.h memory.h gc.h major_gc.h minor_gc.h osdeps.h \
+  prims.h printexc.h reverse.h signals.h stacks.h sys.h startup.h \
+  version.h
 str.o: str.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h int64_native.h
+  ../config/s.h mlvalues.h fail.h int64_native.h
 sys.o: sys.c config.h ../config/m.h ../config/s.h compatibility.h alloc.h \
- misc.h mlvalues.h debugger.h fail.h instruct.h osdeps.h signals.h \
- stacks.h memory.h gc.h major_gc.h freelist.h minor_gc.h sys.h
+  misc.h mlvalues.h debugger.h fail.h instruct.h osdeps.h signals.h \
+  stacks.h memory.h gc.h major_gc.h freelist.h minor_gc.h sys.h
 terminfo.o: terminfo.c config.h ../config/m.h ../config/s.h \
- compatibility.h alloc.h misc.h mlvalues.h fail.h io.h
+  compatibility.h alloc.h misc.h mlvalues.h fail.h io.h
 unix.o: unix.c config.h ../config/m.h ../config/s.h compatibility.h \
- memory.h gc.h mlvalues.h misc.h major_gc.h freelist.h minor_gc.h \
- osdeps.h
+  memory.h gc.h mlvalues.h misc.h major_gc.h freelist.h minor_gc.h \
+  osdeps.h
 weak.o: weak.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h major_gc.h freelist.h memory.h gc.h \
- minor_gc.h
+  ../config/s.h mlvalues.h fail.h major_gc.h freelist.h memory.h gc.h \
+  minor_gc.h
 win32.o: win32.c fail.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
- osdeps.h signals.h sys.h
+  ../config/s.h mlvalues.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
+  osdeps.h signals.h sys.h
 alloc.d.o: alloc.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h custom.h major_gc.h freelist.h memory.h gc.h \
- minor_gc.h stacks.h
+  ../config/s.h mlvalues.h custom.h major_gc.h freelist.h memory.h gc.h \
+  minor_gc.h stacks.h
 array.d.o: array.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h memory.h gc.h major_gc.h freelist.h \
- minor_gc.h
+  ../config/s.h mlvalues.h fail.h memory.h gc.h major_gc.h freelist.h \
+  minor_gc.h
 backtrace.d.o: backtrace.c config.h ../config/m.h ../config/s.h \
- compatibility.h mlvalues.h misc.h alloc.h io.h instruct.h intext.h \
- exec.h fix_code.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
- startup.h stacks.h sys.h backtrace.h
+  compatibility.h mlvalues.h misc.h alloc.h io.h instruct.h intext.h \
+  exec.h fix_code.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
+  startup.h stacks.h sys.h backtrace.h
 callback.d.o: callback.c callback.h compatibility.h mlvalues.h config.h \
- ../config/m.h ../config/s.h misc.h fail.h memory.h gc.h major_gc.h \
- freelist.h minor_gc.h interp.h instruct.h fix_code.h stacks.h
+  ../config/m.h ../config/s.h misc.h fail.h memory.h gc.h major_gc.h \
+  freelist.h minor_gc.h interp.h instruct.h fix_code.h stacks.h
 compact.d.o: compact.c config.h ../config/m.h ../config/s.h compatibility.h \
- finalise.h roots.h misc.h memory.h gc.h mlvalues.h major_gc.h freelist.h \
- minor_gc.h gc_ctrl.h weak.h
+  finalise.h roots.h misc.h memory.h gc.h mlvalues.h major_gc.h \
+  freelist.h minor_gc.h gc_ctrl.h weak.h
 compare.d.o: compare.c custom.h compatibility.h mlvalues.h config.h \
- ../config/m.h ../config/s.h misc.h fail.h memory.h gc.h major_gc.h \
- freelist.h minor_gc.h
+  ../config/m.h ../config/s.h misc.h fail.h memory.h gc.h major_gc.h \
+  freelist.h minor_gc.h
 custom.d.o: custom.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h custom.h fail.h memory.h gc.h major_gc.h \
- freelist.h minor_gc.h
+  ../config/s.h mlvalues.h custom.h fail.h memory.h gc.h major_gc.h \
+  freelist.h minor_gc.h
 debugger.d.o: debugger.c alloc.h compatibility.h misc.h config.h \
- ../config/m.h ../config/s.h mlvalues.h debugger.h fail.h fix_code.h \
- instruct.h intext.h io.h stacks.h memory.h gc.h major_gc.h freelist.h \
- minor_gc.h sys.h
+  ../config/m.h ../config/s.h mlvalues.h debugger.h fail.h fix_code.h \
+  instruct.h intext.h io.h stacks.h memory.h gc.h major_gc.h freelist.h \
+  minor_gc.h sys.h
 dynlink.d.o: dynlink.c config.h ../config/m.h ../config/s.h compatibility.h \
- alloc.h misc.h mlvalues.h dynlink.h fail.h memory.h gc.h major_gc.h \
- freelist.h minor_gc.h osdeps.h prims.h
+  alloc.h misc.h mlvalues.h dynlink.h fail.h memory.h gc.h major_gc.h \
+  freelist.h minor_gc.h osdeps.h prims.h
 extern.d.o: extern.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h custom.h fail.h gc.h intext.h io.h md5.h \
- memory.h major_gc.h freelist.h minor_gc.h reverse.h
+  ../config/s.h mlvalues.h custom.h fail.h gc.h intext.h io.h md5.h \
+  memory.h major_gc.h freelist.h minor_gc.h reverse.h
 fail.d.o: fail.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h io.h gc.h memory.h major_gc.h freelist.h \
- minor_gc.h printexc.h signals.h stacks.h
+  ../config/s.h mlvalues.h fail.h io.h gc.h memory.h major_gc.h \
+  freelist.h minor_gc.h printexc.h signals.h stacks.h
 finalise.d.o: finalise.c callback.h compatibility.h mlvalues.h config.h \
- ../config/m.h ../config/s.h misc.h fail.h roots.h memory.h gc.h \
- major_gc.h freelist.h minor_gc.h signals.h
+  ../config/m.h ../config/s.h misc.h fail.h roots.h memory.h gc.h \
+  major_gc.h freelist.h minor_gc.h signals.h
 fix_code.d.o: fix_code.c config.h ../config/m.h ../config/s.h \
- compatibility.h debugger.h misc.h mlvalues.h fix_code.h instruct.h \
- intext.h io.h md5.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
- reverse.h
+  compatibility.h debugger.h misc.h mlvalues.h fix_code.h instruct.h \
+  intext.h io.h md5.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
+  reverse.h
 floats.d.o: floats.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h memory.h gc.h major_gc.h freelist.h \
- minor_gc.h reverse.h stacks.h
+  ../config/s.h mlvalues.h fail.h memory.h gc.h major_gc.h freelist.h \
+  minor_gc.h reverse.h stacks.h
 freelist.d.o: freelist.c config.h ../config/m.h ../config/s.h \
- compatibility.h freelist.h misc.h mlvalues.h gc.h gc_ctrl.h memory.h \
- major_gc.h minor_gc.h
+  compatibility.h freelist.h misc.h mlvalues.h gc.h gc_ctrl.h memory.h \
+  major_gc.h minor_gc.h
 gc_ctrl.d.o: gc_ctrl.c alloc.h compatibility.h misc.h config.h \
- ../config/m.h ../config/s.h mlvalues.h compact.h custom.h finalise.h \
- roots.h memory.h gc.h major_gc.h freelist.h minor_gc.h gc_ctrl.h \
- stacks.h
+  ../config/m.h ../config/s.h mlvalues.h compact.h custom.h finalise.h \
+  roots.h memory.h gc.h major_gc.h freelist.h minor_gc.h gc_ctrl.h \
+  stacks.h
 globroots.d.o: globroots.c memory.h compatibility.h config.h ../config/m.h \
- ../config/s.h gc.h mlvalues.h misc.h major_gc.h freelist.h minor_gc.h \
- roots.h globroots.h
+  ../config/s.h gc.h mlvalues.h misc.h major_gc.h freelist.h minor_gc.h \
+  roots.h globroots.h
 hash.d.o: hash.c mlvalues.h compatibility.h config.h ../config/m.h \
- ../config/s.h misc.h custom.h memory.h gc.h major_gc.h freelist.h \
- minor_gc.h hash.h int64_native.h
+  ../config/s.h misc.h custom.h memory.h gc.h major_gc.h freelist.h \
+  minor_gc.h hash.h int64_native.h
 instrtrace.d.o: instrtrace.c instruct.h misc.h compatibility.h config.h \
- ../config/m.h ../config/s.h mlvalues.h opnames.h prims.h stacks.h \
- memory.h gc.h major_gc.h freelist.h minor_gc.h
+  ../config/m.h ../config/s.h mlvalues.h opnames.h prims.h stacks.h \
+  memory.h gc.h major_gc.h freelist.h minor_gc.h
 intern.d.o: intern.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h callback.h custom.h fail.h gc.h intext.h io.h \
- md5.h memory.h major_gc.h freelist.h minor_gc.h reverse.h
+  ../config/s.h mlvalues.h callback.h custom.h fail.h gc.h intext.h io.h \
+  md5.h memory.h major_gc.h freelist.h minor_gc.h reverse.h
 interp.d.o: interp.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h backtrace.h callback.h debugger.h fail.h \
- fix_code.h instrtrace.h instruct.h interp.h major_gc.h freelist.h \
- memory.h gc.h minor_gc.h prims.h signals.h stacks.h
+  ../config/s.h mlvalues.h backtrace.h callback.h debugger.h fail.h \
+  fix_code.h instrtrace.h instruct.h interp.h major_gc.h freelist.h \
+  memory.h gc.h minor_gc.h prims.h signals.h stacks.h
 ints.d.o: ints.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h custom.h fail.h intext.h io.h memory.h gc.h \
- major_gc.h freelist.h minor_gc.h int64_native.h
+  ../config/s.h mlvalues.h custom.h fail.h intext.h io.h memory.h gc.h \
+  major_gc.h freelist.h minor_gc.h int64_native.h
 io.d.o: io.c config.h ../config/m.h ../config/s.h compatibility.h alloc.h \
- misc.h mlvalues.h custom.h fail.h io.h memory.h gc.h major_gc.h \
- freelist.h minor_gc.h signals.h sys.h
+  misc.h mlvalues.h custom.h fail.h io.h memory.h gc.h major_gc.h \
+  freelist.h minor_gc.h signals.h sys.h
 lexing.d.o: lexing.c fail.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h stacks.h memory.h gc.h major_gc.h freelist.h \
- minor_gc.h
+  ../config/s.h mlvalues.h stacks.h memory.h gc.h major_gc.h freelist.h \
+  minor_gc.h
 main.d.o: main.c misc.h compatibility.h config.h ../config/m.h \
- ../config/s.h mlvalues.h sys.h
+  ../config/s.h mlvalues.h sys.h
 major_gc.d.o: major_gc.c compact.h config.h ../config/m.h ../config/s.h \
- compatibility.h misc.h custom.h mlvalues.h fail.h finalise.h roots.h \
- memory.h gc.h major_gc.h freelist.h minor_gc.h gc_ctrl.h weak.h
+  compatibility.h misc.h custom.h mlvalues.h fail.h finalise.h roots.h \
+  memory.h gc.h major_gc.h freelist.h minor_gc.h gc_ctrl.h weak.h
 md5.d.o: md5.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h md5.h io.h memory.h gc.h major_gc.h \
- freelist.h minor_gc.h reverse.h
+  ../config/s.h mlvalues.h fail.h md5.h io.h memory.h gc.h major_gc.h \
+  freelist.h minor_gc.h reverse.h
 memory.d.o: memory.c fail.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h freelist.h gc.h gc_ctrl.h major_gc.h memory.h \
- minor_gc.h signals.h
+  ../config/s.h mlvalues.h freelist.h gc.h gc_ctrl.h major_gc.h memory.h \
+  minor_gc.h signals.h
 meta.d.o: meta.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h fix_code.h interp.h intext.h io.h \
- major_gc.h freelist.h memory.h gc.h minor_gc.h prims.h stacks.h
+  ../config/s.h mlvalues.h fail.h fix_code.h interp.h intext.h io.h \
+  major_gc.h freelist.h memory.h gc.h minor_gc.h prims.h stacks.h
 minor_gc.d.o: minor_gc.c config.h ../config/m.h ../config/s.h \
- compatibility.h fail.h misc.h mlvalues.h finalise.h roots.h memory.h \
- gc.h major_gc.h freelist.h minor_gc.h gc_ctrl.h signals.h weak.h
+  compatibility.h fail.h misc.h mlvalues.h finalise.h roots.h memory.h \
+  gc.h major_gc.h freelist.h minor_gc.h gc_ctrl.h signals.h weak.h
 misc.d.o: misc.c config.h ../config/m.h ../config/s.h compatibility.h \
- misc.h memory.h gc.h mlvalues.h major_gc.h freelist.h minor_gc.h
+  misc.h memory.h gc.h mlvalues.h major_gc.h freelist.h minor_gc.h
 obj.d.o: obj.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h gc.h interp.h major_gc.h freelist.h \
- memory.h minor_gc.h prims.h
+  ../config/s.h mlvalues.h fail.h gc.h interp.h major_gc.h freelist.h \
+  memory.h minor_gc.h prims.h
 parsing.d.o: parsing.c config.h ../config/m.h ../config/s.h compatibility.h \
- mlvalues.h misc.h memory.h gc.h major_gc.h freelist.h minor_gc.h alloc.h
+  mlvalues.h misc.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
+  alloc.h
 prims.d.o: prims.c mlvalues.h compatibility.h config.h ../config/m.h \
- ../config/s.h misc.h prims.h
+  ../config/s.h misc.h prims.h
 printexc.d.o: printexc.c backtrace.h mlvalues.h compatibility.h config.h \
- ../config/m.h ../config/s.h misc.h callback.h debugger.h fail.h \
- printexc.h
+  ../config/m.h ../config/s.h misc.h callback.h debugger.h fail.h \
+  printexc.h
 roots.d.o: roots.c finalise.h roots.h misc.h compatibility.h config.h \
- ../config/m.h ../config/s.h memory.h gc.h mlvalues.h major_gc.h \
- freelist.h minor_gc.h globroots.h stacks.h
+  ../config/m.h ../config/s.h memory.h gc.h mlvalues.h major_gc.h \
+  freelist.h minor_gc.h globroots.h stacks.h
 signals.d.o: signals.c alloc.h compatibility.h misc.h config.h \
- ../config/m.h ../config/s.h mlvalues.h callback.h fail.h memory.h gc.h \
- major_gc.h freelist.h minor_gc.h roots.h signals.h signals_machdep.h \
- sys.h
+  ../config/m.h ../config/s.h mlvalues.h callback.h fail.h memory.h gc.h \
+  major_gc.h freelist.h minor_gc.h roots.h signals.h signals_machdep.h \
+  sys.h
 signals_byt.d.o: signals_byt.c config.h ../config/m.h ../config/s.h \
- compatibility.h memory.h gc.h mlvalues.h misc.h major_gc.h freelist.h \
- minor_gc.h osdeps.h signals.h signals_machdep.h
+  compatibility.h memory.h gc.h mlvalues.h misc.h major_gc.h freelist.h \
+  minor_gc.h osdeps.h signals.h signals_machdep.h
 stacks.d.o: stacks.c config.h ../config/m.h ../config/s.h compatibility.h \
- fail.h misc.h mlvalues.h stacks.h memory.h gc.h major_gc.h freelist.h \
- minor_gc.h
+  fail.h misc.h mlvalues.h stacks.h memory.h gc.h major_gc.h freelist.h \
+  minor_gc.h
 startup.d.o: startup.c config.h ../config/m.h ../config/s.h compatibility.h \
- alloc.h misc.h mlvalues.h backtrace.h callback.h custom.h debugger.h \
- dynlink.h exec.h fail.h fix_code.h freelist.h gc_ctrl.h instrtrace.h \
- interp.h intext.h io.h memory.h gc.h major_gc.h minor_gc.h osdeps.h \
- prims.h printexc.h reverse.h signals.h stacks.h sys.h startup.h \
- version.h
+  alloc.h misc.h mlvalues.h backtrace.h callback.h custom.h debugger.h \
+  dynlink.h exec.h fail.h fix_code.h freelist.h gc_ctrl.h instrtrace.h \
+  interp.h intext.h io.h memory.h gc.h major_gc.h minor_gc.h osdeps.h \
+  prims.h printexc.h reverse.h signals.h stacks.h sys.h startup.h \
+  version.h
 str.d.o: str.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h int64_native.h
+  ../config/s.h mlvalues.h fail.h int64_native.h
 sys.d.o: sys.c config.h ../config/m.h ../config/s.h compatibility.h alloc.h \
- misc.h mlvalues.h debugger.h fail.h instruct.h osdeps.h signals.h \
- stacks.h memory.h gc.h major_gc.h freelist.h minor_gc.h sys.h
+  misc.h mlvalues.h debugger.h fail.h instruct.h osdeps.h signals.h \
+  stacks.h memory.h gc.h major_gc.h freelist.h minor_gc.h sys.h
 terminfo.d.o: terminfo.c config.h ../config/m.h ../config/s.h \
- compatibility.h alloc.h misc.h mlvalues.h fail.h io.h
+  compatibility.h alloc.h misc.h mlvalues.h fail.h io.h
 unix.d.o: unix.c config.h ../config/m.h ../config/s.h compatibility.h \
- memory.h gc.h mlvalues.h misc.h major_gc.h freelist.h minor_gc.h \
- osdeps.h
+  memory.h gc.h mlvalues.h misc.h major_gc.h freelist.h minor_gc.h \
+  osdeps.h
 weak.d.o: weak.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h major_gc.h freelist.h memory.h gc.h \
- minor_gc.h
+  ../config/s.h mlvalues.h fail.h major_gc.h freelist.h memory.h gc.h \
+  minor_gc.h
 win32.d.o: win32.c fail.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
- osdeps.h signals.h sys.h
+  ../config/s.h mlvalues.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
+  osdeps.h signals.h sys.h
 alloc.pic.o: alloc.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h custom.h major_gc.h freelist.h memory.h gc.h \
- minor_gc.h stacks.h
+  ../config/s.h mlvalues.h custom.h major_gc.h freelist.h memory.h gc.h \
+  minor_gc.h stacks.h
 array.pic.o: array.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h memory.h gc.h major_gc.h freelist.h \
- minor_gc.h
+  ../config/s.h mlvalues.h fail.h memory.h gc.h major_gc.h freelist.h \
+  minor_gc.h
 backtrace.pic.o: backtrace.c config.h ../config/m.h ../config/s.h \
- compatibility.h mlvalues.h misc.h alloc.h io.h instruct.h intext.h \
- exec.h fix_code.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
- startup.h stacks.h sys.h backtrace.h
+  compatibility.h mlvalues.h misc.h alloc.h io.h instruct.h intext.h \
+  exec.h fix_code.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
+  startup.h stacks.h sys.h backtrace.h
 callback.pic.o: callback.c callback.h compatibility.h mlvalues.h config.h \
- ../config/m.h ../config/s.h misc.h fail.h memory.h gc.h major_gc.h \
- freelist.h minor_gc.h interp.h instruct.h fix_code.h stacks.h
+  ../config/m.h ../config/s.h misc.h fail.h memory.h gc.h major_gc.h \
+  freelist.h minor_gc.h interp.h instruct.h fix_code.h stacks.h
 compact.pic.o: compact.c config.h ../config/m.h ../config/s.h compatibility.h \
- finalise.h roots.h misc.h memory.h gc.h mlvalues.h major_gc.h freelist.h \
- minor_gc.h gc_ctrl.h weak.h
+  finalise.h roots.h misc.h memory.h gc.h mlvalues.h major_gc.h \
+  freelist.h minor_gc.h gc_ctrl.h weak.h
 compare.pic.o: compare.c custom.h compatibility.h mlvalues.h config.h \
- ../config/m.h ../config/s.h misc.h fail.h memory.h gc.h major_gc.h \
- freelist.h minor_gc.h
+  ../config/m.h ../config/s.h misc.h fail.h memory.h gc.h major_gc.h \
+  freelist.h minor_gc.h
 custom.pic.o: custom.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h custom.h fail.h memory.h gc.h major_gc.h \
- freelist.h minor_gc.h
+  ../config/s.h mlvalues.h custom.h fail.h memory.h gc.h major_gc.h \
+  freelist.h minor_gc.h
 debugger.pic.o: debugger.c alloc.h compatibility.h misc.h config.h \
- ../config/m.h ../config/s.h mlvalues.h debugger.h fail.h fix_code.h \
- instruct.h intext.h io.h stacks.h memory.h gc.h major_gc.h freelist.h \
- minor_gc.h sys.h
+  ../config/m.h ../config/s.h mlvalues.h debugger.h fail.h fix_code.h \
+  instruct.h intext.h io.h stacks.h memory.h gc.h major_gc.h freelist.h \
+  minor_gc.h sys.h
 dynlink.pic.o: dynlink.c config.h ../config/m.h ../config/s.h compatibility.h \
- alloc.h misc.h mlvalues.h dynlink.h fail.h memory.h gc.h major_gc.h \
- freelist.h minor_gc.h osdeps.h prims.h
+  alloc.h misc.h mlvalues.h dynlink.h fail.h memory.h gc.h major_gc.h \
+  freelist.h minor_gc.h osdeps.h prims.h
 extern.pic.o: extern.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h custom.h fail.h gc.h intext.h io.h md5.h \
- memory.h major_gc.h freelist.h minor_gc.h reverse.h
+  ../config/s.h mlvalues.h custom.h fail.h gc.h intext.h io.h md5.h \
+  memory.h major_gc.h freelist.h minor_gc.h reverse.h
 fail.pic.o: fail.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h io.h gc.h memory.h major_gc.h freelist.h \
- minor_gc.h printexc.h signals.h stacks.h
+  ../config/s.h mlvalues.h fail.h io.h gc.h memory.h major_gc.h \
+  freelist.h minor_gc.h printexc.h signals.h stacks.h
 finalise.pic.o: finalise.c callback.h compatibility.h mlvalues.h config.h \
- ../config/m.h ../config/s.h misc.h fail.h roots.h memory.h gc.h \
- major_gc.h freelist.h minor_gc.h signals.h
+  ../config/m.h ../config/s.h misc.h fail.h roots.h memory.h gc.h \
+  major_gc.h freelist.h minor_gc.h signals.h
 fix_code.pic.o: fix_code.c config.h ../config/m.h ../config/s.h \
- compatibility.h debugger.h misc.h mlvalues.h fix_code.h instruct.h \
- intext.h io.h md5.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
- reverse.h
+  compatibility.h debugger.h misc.h mlvalues.h fix_code.h instruct.h \
+  intext.h io.h md5.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
+  reverse.h
 floats.pic.o: floats.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h memory.h gc.h major_gc.h freelist.h \
- minor_gc.h reverse.h stacks.h
+  ../config/s.h mlvalues.h fail.h memory.h gc.h major_gc.h freelist.h \
+  minor_gc.h reverse.h stacks.h
 freelist.pic.o: freelist.c config.h ../config/m.h ../config/s.h \
- compatibility.h freelist.h misc.h mlvalues.h gc.h gc_ctrl.h memory.h \
- major_gc.h minor_gc.h
+  compatibility.h freelist.h misc.h mlvalues.h gc.h gc_ctrl.h memory.h \
+  major_gc.h minor_gc.h
 gc_ctrl.pic.o: gc_ctrl.c alloc.h compatibility.h misc.h config.h \
- ../config/m.h ../config/s.h mlvalues.h compact.h custom.h finalise.h \
- roots.h memory.h gc.h major_gc.h freelist.h minor_gc.h gc_ctrl.h \
- stacks.h
+  ../config/m.h ../config/s.h mlvalues.h compact.h custom.h finalise.h \
+  roots.h memory.h gc.h major_gc.h freelist.h minor_gc.h gc_ctrl.h \
+  stacks.h
 globroots.pic.o: globroots.c memory.h compatibility.h config.h ../config/m.h \
- ../config/s.h gc.h mlvalues.h misc.h major_gc.h freelist.h minor_gc.h \
- roots.h globroots.h
+  ../config/s.h gc.h mlvalues.h misc.h major_gc.h freelist.h minor_gc.h \
+  roots.h globroots.h
 hash.pic.o: hash.c mlvalues.h compatibility.h config.h ../config/m.h \
- ../config/s.h misc.h custom.h memory.h gc.h major_gc.h freelist.h \
- minor_gc.h hash.h int64_native.h
+  ../config/s.h misc.h custom.h memory.h gc.h major_gc.h freelist.h \
+  minor_gc.h hash.h int64_native.h
 instrtrace.pic.o: instrtrace.c
 intern.pic.o: intern.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h callback.h custom.h fail.h gc.h intext.h io.h \
- md5.h memory.h major_gc.h freelist.h minor_gc.h reverse.h
+  ../config/s.h mlvalues.h callback.h custom.h fail.h gc.h intext.h io.h \
+  md5.h memory.h major_gc.h freelist.h minor_gc.h reverse.h
 interp.pic.o: interp.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h backtrace.h callback.h debugger.h fail.h \
- fix_code.h instrtrace.h instruct.h interp.h major_gc.h freelist.h \
- memory.h gc.h minor_gc.h prims.h signals.h stacks.h jumptbl.h
+  ../config/s.h mlvalues.h backtrace.h callback.h debugger.h fail.h \
+  fix_code.h instrtrace.h instruct.h interp.h major_gc.h freelist.h \
+  memory.h gc.h minor_gc.h prims.h signals.h stacks.h jumptbl.h
 ints.pic.o: ints.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h custom.h fail.h intext.h io.h memory.h gc.h \
- major_gc.h freelist.h minor_gc.h int64_native.h
+  ../config/s.h mlvalues.h custom.h fail.h intext.h io.h memory.h gc.h \
+  major_gc.h freelist.h minor_gc.h int64_native.h
 io.pic.o: io.c config.h ../config/m.h ../config/s.h compatibility.h alloc.h \
- misc.h mlvalues.h custom.h fail.h io.h memory.h gc.h major_gc.h \
- freelist.h minor_gc.h signals.h sys.h
+  misc.h mlvalues.h custom.h fail.h io.h memory.h gc.h major_gc.h \
+  freelist.h minor_gc.h signals.h sys.h
 lexing.pic.o: lexing.c fail.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h stacks.h memory.h gc.h major_gc.h freelist.h \
- minor_gc.h
+  ../config/s.h mlvalues.h stacks.h memory.h gc.h major_gc.h freelist.h \
+  minor_gc.h
 main.pic.o: main.c misc.h compatibility.h config.h ../config/m.h \
- ../config/s.h mlvalues.h sys.h
+  ../config/s.h mlvalues.h sys.h
 major_gc.pic.o: major_gc.c compact.h config.h ../config/m.h ../config/s.h \
- compatibility.h misc.h custom.h mlvalues.h fail.h finalise.h roots.h \
- memory.h gc.h major_gc.h freelist.h minor_gc.h gc_ctrl.h weak.h
+  compatibility.h misc.h custom.h mlvalues.h fail.h finalise.h roots.h \
+  memory.h gc.h major_gc.h freelist.h minor_gc.h gc_ctrl.h weak.h
 md5.pic.o: md5.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h md5.h io.h memory.h gc.h major_gc.h \
- freelist.h minor_gc.h reverse.h
+  ../config/s.h mlvalues.h fail.h md5.h io.h memory.h gc.h major_gc.h \
+  freelist.h minor_gc.h reverse.h
 memory.pic.o: memory.c fail.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h freelist.h gc.h gc_ctrl.h major_gc.h memory.h \
- minor_gc.h signals.h
+  ../config/s.h mlvalues.h freelist.h gc.h gc_ctrl.h major_gc.h memory.h \
+  minor_gc.h signals.h
 meta.pic.o: meta.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h fix_code.h interp.h intext.h io.h \
- major_gc.h freelist.h memory.h gc.h minor_gc.h prims.h stacks.h
+  ../config/s.h mlvalues.h fail.h fix_code.h interp.h intext.h io.h \
+  major_gc.h freelist.h memory.h gc.h minor_gc.h prims.h stacks.h
 minor_gc.pic.o: minor_gc.c config.h ../config/m.h ../config/s.h \
- compatibility.h fail.h misc.h mlvalues.h finalise.h roots.h memory.h \
- gc.h major_gc.h freelist.h minor_gc.h gc_ctrl.h signals.h weak.h
+  compatibility.h fail.h misc.h mlvalues.h finalise.h roots.h memory.h \
+  gc.h major_gc.h freelist.h minor_gc.h gc_ctrl.h signals.h weak.h
 misc.pic.o: misc.c config.h ../config/m.h ../config/s.h compatibility.h \
- misc.h memory.h gc.h mlvalues.h major_gc.h freelist.h minor_gc.h
+  misc.h memory.h gc.h mlvalues.h major_gc.h freelist.h minor_gc.h
 obj.pic.o: obj.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h gc.h interp.h major_gc.h freelist.h \
- memory.h minor_gc.h prims.h
+  ../config/s.h mlvalues.h fail.h gc.h interp.h major_gc.h freelist.h \
+  memory.h minor_gc.h prims.h
 parsing.pic.o: parsing.c config.h ../config/m.h ../config/s.h compatibility.h \
- mlvalues.h misc.h memory.h gc.h major_gc.h freelist.h minor_gc.h alloc.h
+  mlvalues.h misc.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
+  alloc.h
 prims.pic.o: prims.c mlvalues.h compatibility.h config.h ../config/m.h \
- ../config/s.h misc.h prims.h
+  ../config/s.h misc.h prims.h
 printexc.pic.o: printexc.c backtrace.h mlvalues.h compatibility.h config.h \
- ../config/m.h ../config/s.h misc.h callback.h debugger.h fail.h \
- printexc.h
+  ../config/m.h ../config/s.h misc.h callback.h debugger.h fail.h \
+  printexc.h
 roots.pic.o: roots.c finalise.h roots.h misc.h compatibility.h config.h \
- ../config/m.h ../config/s.h memory.h gc.h mlvalues.h major_gc.h \
- freelist.h minor_gc.h globroots.h stacks.h
+  ../config/m.h ../config/s.h memory.h gc.h mlvalues.h major_gc.h \
+  freelist.h minor_gc.h globroots.h stacks.h
 signals.pic.o: signals.c alloc.h compatibility.h misc.h config.h \
- ../config/m.h ../config/s.h mlvalues.h callback.h fail.h memory.h gc.h \
- major_gc.h freelist.h minor_gc.h roots.h signals.h signals_machdep.h \
- sys.h
+  ../config/m.h ../config/s.h mlvalues.h callback.h fail.h memory.h gc.h \
+  major_gc.h freelist.h minor_gc.h roots.h signals.h signals_machdep.h \
+  sys.h
 signals_byt.pic.o: signals_byt.c config.h ../config/m.h ../config/s.h \
- compatibility.h memory.h gc.h mlvalues.h misc.h major_gc.h freelist.h \
- minor_gc.h osdeps.h signals.h signals_machdep.h
+  compatibility.h memory.h gc.h mlvalues.h misc.h major_gc.h freelist.h \
+  minor_gc.h osdeps.h signals.h signals_machdep.h
 stacks.pic.o: stacks.c config.h ../config/m.h ../config/s.h compatibility.h \
- fail.h misc.h mlvalues.h stacks.h memory.h gc.h major_gc.h freelist.h \
- minor_gc.h
+  fail.h misc.h mlvalues.h stacks.h memory.h gc.h major_gc.h freelist.h \
+  minor_gc.h
 startup.pic.o: startup.c config.h ../config/m.h ../config/s.h compatibility.h \
- alloc.h misc.h mlvalues.h backtrace.h callback.h custom.h debugger.h \
- dynlink.h exec.h fail.h fix_code.h freelist.h gc_ctrl.h instrtrace.h \
- interp.h intext.h io.h memory.h gc.h major_gc.h minor_gc.h osdeps.h \
- prims.h printexc.h reverse.h signals.h stacks.h sys.h startup.h \
- version.h
+  alloc.h misc.h mlvalues.h backtrace.h callback.h custom.h debugger.h \
+  dynlink.h exec.h fail.h fix_code.h freelist.h gc_ctrl.h instrtrace.h \
+  interp.h intext.h io.h memory.h gc.h major_gc.h minor_gc.h osdeps.h \
+  prims.h printexc.h reverse.h signals.h stacks.h sys.h startup.h \
+  version.h
 str.pic.o: str.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h int64_native.h
+  ../config/s.h mlvalues.h fail.h int64_native.h
 sys.pic.o: sys.c config.h ../config/m.h ../config/s.h compatibility.h alloc.h \
- misc.h mlvalues.h debugger.h fail.h instruct.h osdeps.h signals.h \
- stacks.h memory.h gc.h major_gc.h freelist.h minor_gc.h sys.h
+  misc.h mlvalues.h debugger.h fail.h instruct.h osdeps.h signals.h \
+  stacks.h memory.h gc.h major_gc.h freelist.h minor_gc.h sys.h
 terminfo.pic.o: terminfo.c config.h ../config/m.h ../config/s.h \
- compatibility.h alloc.h misc.h mlvalues.h fail.h io.h
+  compatibility.h alloc.h misc.h mlvalues.h fail.h io.h
 unix.pic.o: unix.c config.h ../config/m.h ../config/s.h compatibility.h \
- memory.h gc.h mlvalues.h misc.h major_gc.h freelist.h minor_gc.h \
- osdeps.h
+  memory.h gc.h mlvalues.h misc.h major_gc.h freelist.h minor_gc.h \
+  osdeps.h
 weak.pic.o: weak.c alloc.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h fail.h major_gc.h freelist.h memory.h gc.h \
- minor_gc.h
+  ../config/s.h mlvalues.h fail.h major_gc.h freelist.h memory.h gc.h \
+  minor_gc.h
 win32.pic.o: win32.c fail.h compatibility.h misc.h config.h ../config/m.h \
- ../config/s.h mlvalues.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
- osdeps.h signals.h sys.h
+  ../config/s.h mlvalues.h memory.h gc.h major_gc.h freelist.h minor_gc.h \
+  osdeps.h signals.h sys.h
diff --git a/debugger/.depend b/debugger/.depend
index 13de8ede13..b62541619a 100644
--- a/debugger/.depend
+++ b/debugger/.depend
@@ -164,11 +164,13 @@ program_loading.cmx : unix_tools.cmx $(UNIXDIR)/unix.cmx \
 program_management.cmo : unix_tools.cmi $(UNIXDIR)/unix.cmi \
     time_travel.cmi symbols.cmi question.cmi program_loading.cmi \
     primitives.cmi parameters.cmi int64ops.cmi input_handling.cmi history.cmi \
-    debugger_config.cmi breakpoints.cmi program_management.cmi
+    ../typing/envaux.cmi debugger_config.cmi ../utils/config.cmi \
+    breakpoints.cmi program_management.cmi
 program_management.cmx : unix_tools.cmx $(UNIXDIR)/unix.cmx \
     time_travel.cmx symbols.cmx question.cmx program_loading.cmx \
     primitives.cmx parameters.cmx int64ops.cmx input_handling.cmx history.cmx \
-    debugger_config.cmx breakpoints.cmx program_management.cmi
+    ../typing/envaux.cmx debugger_config.cmx ../utils/config.cmx \
+    breakpoints.cmx program_management.cmi
 question.cmo : primitives.cmi lexer.cmi input_handling.cmi question.cmi
 question.cmx : primitives.cmx lexer.cmx input_handling.cmx question.cmi
 show_information.cmo : symbols.cmi source.cmi show_source.cmi printval.cmi \
diff --git a/debugger/Makefile.shared b/debugger/Makefile.shared
index 249e8b4c40..fed1d26dab 100644
--- a/debugger/Makefile.shared
+++ b/debugger/Makefile.shared
@@ -14,7 +14,7 @@ include ../config/Makefile
 
 ROOTDIR=..
 CAMLC=$(ROOTDIR)/boot/ocamlrun $(ROOTDIR)/ocamlc -nostdlib -I $(ROOTDIR)/stdlib
-COMPFLAGS=-warn-error A $(INCLUDES)
+COMPFLAGS=-warn-error A -safe-string $(INCLUDES)
 LINKFLAGS=-linkall -I $(UNIXDIR)
 CAMLYACC=../boot/ocamlyacc
 YACCFLAGS=
diff --git a/debugger/debugcom.ml b/debugger/debugcom.ml
index 72702da168..ac91df799f 100644
--- a/debugger/debugcom.ml
+++ b/debugger/debugcom.ml
@@ -187,10 +187,10 @@ let set_trap_barrier pos =
 let value_size = if 1 lsl 31 = 0 then 4 else 8
 
 let input_remote_value ic =
-  Misc.input_bytes ic value_size
+  really_input_string ic value_size
 
 let output_remote_value ic v =
-  output ic v 0 value_size
+  output_substring ic v 0 value_size
 
 exception Marshalling_error
 
@@ -244,7 +244,7 @@ module Remote_value =
           if input_byte !conn.io_in = 0 then
             Remote(input_remote_value !conn.io_in)
           else begin
-            let buf = Misc.input_bytes !conn.io_in 8 in
+            let buf = really_input_string !conn.io_in 8 in
             let floatbuf = float n (* force allocation of a new float *) in
             String.unsafe_blit buf 0 (Obj.magic floatbuf) 0 8;
             Local(Obj.repr floatbuf)
diff --git a/debugger/input_handling.mli b/debugger/input_handling.mli
index 749687ce3b..66db47f15f 100644
--- a/debugger/input_handling.mli
+++ b/debugger/input_handling.mli
@@ -49,7 +49,7 @@ val current_prompt : string ref
 (* Where the user input come from. *)
 val user_channel : io_channel ref
 
-val read_user_input : string -> int -> int
+val read_user_input : bytes -> int -> int
 
 (* Stop reading user input. *)
 val stop_user_input : unit -> unit
diff --git a/debugger/program_management.ml b/debugger/program_management.ml
index 1e29b138f8..48118573ee 100644
--- a/debugger/program_management.ml
+++ b/debugger/program_management.ml
@@ -30,7 +30,7 @@ open Time_travel
 let file_name = ref (None : string option)
 
 (* Default connection handler. *)
-let buffer = String.create 1024
+let buffer = Bytes.create 1024
 let control_connection pid fd =
   if (read fd.io_fd buffer 0 1024) = 0 then
     forget_process fd pid
diff --git a/debugger/source.ml b/debugger/source.ml
index c68df3373c..af69fbc7bf 100644
--- a/debugger/source.ml
+++ b/debugger/source.ml
@@ -74,7 +74,7 @@ let get_buffer pos mdle =
   try List.assoc mdle !buffer_list with
     Not_found ->
       let inchan = open_in_bin (source_of_module pos mdle) in
-      let content = Misc.input_bytes inchan (in_channel_length inchan) in
+      let content = really_input_string inchan (in_channel_length inchan) in
       let buffer = (content, ref []) in
       buffer_list :=
         (list_truncate !buffer_max_count ((mdle, buffer)::!buffer_list));
diff --git a/driver/compenv.ml b/driver/compenv.ml
index a40083275b..e2a90d29a6 100644
--- a/driver/compenv.ml
+++ b/driver/compenv.ml
@@ -158,6 +158,7 @@ let read_OCAMLPARAM ppf position =
       | "nolabels" -> set "nolabels" [ classic ] v
       | "principal" -> set "principal"  [ principal ] v
       | "rectypes" -> set "rectypes" [ recursive_types ] v
+      | "safe-string" -> clear "safe-string" [ unsafe_string ] v
       | "strict-sequence" -> set "strict-sequence" [ strict_sequence ] v
       | "thread" -> set "thread" [ use_threads ] v
       | "unsafe" -> set "unsafe" [ fast ] v
diff --git a/driver/compmisc.ml b/driver/compmisc.ml
index 8f974f4be1..b97ba6c74e 100644
--- a/driver/compmisc.ml
+++ b/driver/compmisc.ml
@@ -47,11 +47,13 @@ let open_implicit_module m env =
 
 let initial_env () =
   Ident.reinit();
+  let initial =
+    if !Clflags.unsafe_string then Env.initial_unsafe_string
+    else Env.initial_safe_string
+  in
   let env =
-    if !Clflags.nopervasives
-    then Env.initial
-    else
-      open_implicit_module "Pervasives" Env.initial
+    if !Clflags.nopervasives then initial else
+    open_implicit_module "Pervasives" initial
   in
   List.fold_left (fun env m ->
     open_implicit_module m env
diff --git a/driver/main.ml b/driver/main.ml
index cbb6459993..44df1208be 100644
--- a/driver/main.ml
+++ b/driver/main.ml
@@ -109,12 +109,14 @@ module Options = Main_args.Make_bytecomp_options (struct
   let _principal = set principal
   let _rectypes = set recursive_types
   let _runtime_variant s = runtime_variant := s
+  let _safe_string = unset unsafe_string
   let _short_paths = unset real_paths
   let _strict_sequence = set strict_sequence
   let _thread = set use_threads
   let _trans_mod = set transparent_modules
   let _vmthread = set use_vmthreads
   let _unsafe = set fast
+  let _unsafe_string = set unsafe_string
   let _use_prims s = use_prims := s
   let _use_runtime s = use_runtime := s
   let _v () = print_version_and_library "compiler"
@@ -160,7 +162,8 @@ let main () =
       Compmisc.init_path false;
       let extracted_output = extract_output !output_name in
       let revd = get_objfiles () in
-      Bytepackager.package_files ppf revd (extracted_output);
+      Bytepackager.package_files ppf (Compmisc.initial_env ())
+        revd (extracted_output);
       Warnings.check_fatal ();
     end
     else if not !compile_only && !objfiles <> [] then begin
diff --git a/driver/main_args.ml b/driver/main_args.ml
index f72a08fffd..1444ae4571 100644
--- a/driver/main_args.ml
+++ b/driver/main_args.ml
@@ -247,6 +247,14 @@ let mk_S f =
   "-S", Arg.Unit f, " Keep intermediate assembly file"
 ;;
 
+let mk_safe_string f =
+  "-safe-string", Arg.Unit f, " Make strings immutable"
+;;
+
+let mk_shared f =
+  "-shared", Arg.Unit f, " Produce a dynlinkable plugin"
+;;
+
 let mk_short_paths f =
   "-short-paths", Arg.Unit f, " Shorten paths in types"
 ;;
@@ -260,10 +268,6 @@ let mk_strict_sequence f =
   " Left-hand part of a sequence must have type unit"
 ;;
 
-let mk_shared f =
-  "-shared", Arg.Unit f, " Produce a dynlinkable plugin"
-;;
-
 let mk_thread f =
   "-thread", Arg.Unit f,
   " Generate code that supports the system threads library"
@@ -278,6 +282,10 @@ let mk_unsafe f =
   " Do not compile bounds checking on array and string access"
 ;;
 
+let mk_unsafe_string f =
+  "-unsafe-string", Arg.Unit f, " Make strings mutable (default)"
+;;
+
 let mk_use_runtime f =
   "-use-runtime", Arg.String f,
   "<file>  Generate bytecode for the given runtime system"
@@ -475,12 +483,14 @@ module type Bytecomp_options = sig
   val _principal : unit -> unit
   val _rectypes : unit -> unit
   val _runtime_variant : string -> unit
+  val _safe_string : unit -> unit
   val _short_paths : unit -> unit
   val _strict_sequence : unit -> unit
   val _trans_mod : unit -> unit
   val _thread : unit -> unit
   val _vmthread : unit -> unit
   val _unsafe : unit -> unit
+  val _unsafe_string : unit -> unit
   val _use_runtime : string -> unit
   val _v : unit -> unit
   val _version : unit -> unit
@@ -518,11 +528,13 @@ module type Bytetop_options = sig
   val _ppx : string -> unit
   val _principal : unit -> unit
   val _rectypes : unit -> unit
+  val _safe_string : unit -> unit
   val _short_paths : unit -> unit
   val _stdin: unit -> unit
   val _strict_sequence : unit -> unit
   val _trans_mod : unit -> unit
   val _unsafe : unit -> unit
+  val _unsafe_string : unit -> unit
   val _version : unit -> unit
   val _vnum : unit -> unit
   val _w : string -> unit
@@ -578,12 +590,14 @@ module type Optcomp_options = sig
   val _rectypes : unit -> unit
   val _runtime_variant : string -> unit
   val _S : unit -> unit
+  val _safe_string : unit -> unit
   val _shared : unit -> unit
   val _short_paths : unit -> unit
   val _strict_sequence : unit -> unit
   val _trans_mod : unit -> unit
   val _thread : unit -> unit
   val _unsafe : unit -> unit
+  val _unsafe_string : unit -> unit
   val _v : unit -> unit
   val _verbose : unit -> unit
   val _version : unit -> unit
@@ -636,11 +650,13 @@ module type Opttop_options = sig
   val _principal : unit -> unit
   val _rectypes : unit -> unit
   val _S : unit -> unit
+  val _safe_string : unit -> unit
   val _short_paths : unit -> unit
   val _stdin : unit -> unit
   val _strict_sequence : unit -> unit
   val _trans_mod : unit -> unit
   val _unsafe : unit -> unit
+  val _unsafe_string : unit -> unit
   val _version : unit -> unit
   val _vnum : unit -> unit
   val _w : string -> unit
@@ -719,11 +735,13 @@ struct
     mk_principal F._principal;
     mk_rectypes F._rectypes;
     mk_runtime_variant F._runtime_variant;
+    mk_safe_string F._safe_string;
     mk_short_paths F._short_paths;
     mk_strict_sequence F._strict_sequence;
     mk_trans_mod F._trans_mod;
     mk_thread F._thread;
     mk_unsafe F._unsafe;
+    mk_unsafe_string F._unsafe_string;
     mk_use_runtime F._use_runtime;
     mk_use_runtime_2 F._use_runtime;
     mk_v F._v;
@@ -765,11 +783,13 @@ struct
     mk_ppx F._ppx;
     mk_principal F._principal;
     mk_rectypes F._rectypes;
+    mk_safe_string F._safe_string;
     mk_short_paths F._short_paths;
     mk_stdin F._stdin;
     mk_strict_sequence F._strict_sequence;
     mk_trans_mod F._trans_mod;
     mk_unsafe F._unsafe;
+    mk_unsafe_string F._unsafe_string;
     mk_version F._version;
     mk_vnum F._vnum;
     mk_w F._w;
@@ -828,12 +848,14 @@ struct
     mk_rectypes F._rectypes;
     mk_runtime_variant F._runtime_variant;
     mk_S F._S;
+    mk_safe_string F._safe_string;
     mk_shared F._shared;
     mk_short_paths F._short_paths;
     mk_strict_sequence F._strict_sequence;
     mk_trans_mod F._trans_mod;
     mk_thread F._thread;
     mk_unsafe F._unsafe;
+    mk_unsafe_string F._unsafe_string;
     mk_v F._v;
     mk_verbose F._verbose;
     mk_version F._version;
@@ -887,11 +909,13 @@ module Make_opttop_options (F : Opttop_options) = struct
     mk_principal F._principal;
     mk_rectypes F._rectypes;
     mk_S F._S;
+    mk_safe_string F._safe_string;
     mk_short_paths F._short_paths;
     mk_stdin F._stdin;
     mk_strict_sequence F._strict_sequence;
     mk_trans_mod F._trans_mod;
     mk_unsafe F._unsafe;
+    mk_unsafe_string F._unsafe_string;
     mk_version F._version;
     mk_vnum F._vnum;
     mk_w F._w;
diff --git a/driver/main_args.mli b/driver/main_args.mli
index 7d957d0095..98d294f87d 100644
--- a/driver/main_args.mli
+++ b/driver/main_args.mli
@@ -48,12 +48,14 @@ module type Bytecomp_options =
     val _principal : unit -> unit
     val _rectypes : unit -> unit
     val _runtime_variant : string -> unit
+    val _safe_string : unit -> unit
     val _short_paths : unit -> unit
     val _strict_sequence : unit -> unit
     val _trans_mod : unit -> unit
     val _thread : unit -> unit
     val _vmthread : unit -> unit
     val _unsafe : unit -> unit
+    val _unsafe_string : unit -> unit
     val _use_runtime : string -> unit
     val _v : unit -> unit
     val _version : unit -> unit
@@ -92,11 +94,13 @@ module type Bytetop_options = sig
   val _ppx : string -> unit
   val _principal : unit -> unit
   val _rectypes : unit -> unit
+  val _safe_string : unit -> unit
   val _short_paths : unit -> unit
   val _stdin : unit -> unit
   val _strict_sequence : unit -> unit
   val _trans_mod : unit -> unit
   val _unsafe : unit -> unit
+  val _unsafe_string : unit -> unit
   val _version : unit -> unit
   val _vnum : unit -> unit
   val _w : string -> unit
@@ -152,12 +156,14 @@ module type Optcomp_options = sig
   val _rectypes : unit -> unit
   val _runtime_variant : string -> unit
   val _S : unit -> unit
+  val _safe_string : unit -> unit
   val _shared : unit -> unit
   val _short_paths : unit -> unit
   val _strict_sequence : unit -> unit
   val _trans_mod : unit -> unit
   val _thread : unit -> unit
   val _unsafe : unit -> unit
+  val _unsafe_string : unit -> unit
   val _v : unit -> unit
   val _verbose : unit -> unit
   val _version : unit -> unit
@@ -210,11 +216,13 @@ module type Opttop_options = sig
   val _principal : unit -> unit
   val _rectypes : unit -> unit
   val _S : unit -> unit
+  val _safe_string : unit -> unit
   val _short_paths : unit -> unit
   val _stdin : unit -> unit
   val _strict_sequence : unit -> unit
   val _trans_mod : unit -> unit
   val _unsafe : unit -> unit
+  val _unsafe_string : unit -> unit
   val _version : unit -> unit
   val _vnum : unit -> unit
   val _w : string -> unit
diff --git a/driver/optmain.ml b/driver/optmain.ml
index c8060b6a91..8285c6deb7 100644
--- a/driver/optmain.ml
+++ b/driver/optmain.ml
@@ -109,6 +109,7 @@ module Options = Main_args.Make_optcomp_options (struct
   let _principal = set principal
   let _rectypes = set recursive_types
   let _runtime_variant s = runtime_variant := s
+  let _safe_string = clear unsafe_string
   let _short_paths = clear real_paths
   let _strict_sequence = set strict_sequence
   let _trans_mod = set transparent_modules
@@ -116,6 +117,7 @@ module Options = Main_args.Make_optcomp_options (struct
   let _S = set keep_asm_file
   let _thread = set use_threads
   let _unsafe = set fast
+  let _unsafe_string = set unsafe_string
   let _v () = print_version_and_library "native-code compiler"
   let _version () = print_version_string ()
   let _vnum () = print_version_string ()
@@ -174,7 +176,8 @@ let main () =
     else if !make_package then begin
       Compmisc.init_path true;
       let target = extract_output !output_name in
-      Asmpackager.package_files ppf (get_objfiles ()) target;
+      Asmpackager.package_files ppf (Compmisc.initial_env ())
+        (get_objfiles ()) target;
       Warnings.check_fatal ();
     end
     else if !shared then begin
diff --git a/driver/pparse.ml b/driver/pparse.ml
index 7f9974da7a..9912b3ad09 100644
--- a/driver/pparse.ml
+++ b/driver/pparse.ml
@@ -64,7 +64,7 @@ let apply_rewriter magic fn_in ppx =
   (* check magic before passing to the next ppx *)
   let ic = open_in_bin fn_out in
   let buffer =
-    try Misc.input_bytes ic (String.length magic) with End_of_file -> "" in
+    try really_input_string ic (String.length magic) with End_of_file -> "" in
   close_in ic;
   if buffer <> magic then begin
     Misc.remove_file fn_out;
@@ -75,7 +75,7 @@ let apply_rewriter magic fn_in ppx =
 let read_ast magic fn =
   let ic = open_in_bin fn in
   try
-    let buffer = Misc.input_bytes ic (String.length magic) in
+    let buffer = really_input_string ic (String.length magic) in
     assert(buffer = magic); (* already checked by apply_rewriter *)
     Location.input_name := input_value ic;
     let ast = input_value ic in
@@ -105,7 +105,7 @@ let file ppf inputfile parse_fun ast_magic =
   let ic = open_in_bin inputfile in
   let is_ast_file =
     try
-      let buffer = Misc.input_bytes ic (String.length ast_magic) in
+      let buffer = really_input_string ic (String.length ast_magic) in
       if buffer = ast_magic then true
       else if String.sub buffer 0 9 = String.sub ast_magic 0 9 then
         raise Outdated_version
diff --git a/lex/Makefile b/lex/Makefile
index e3cbd320be..cb5df8b41c 100644
--- a/lex/Makefile
+++ b/lex/Makefile
@@ -13,7 +13,7 @@
 # The lexer generator
 CAMLC=../boot/ocamlrun ../boot/ocamlc -strict-sequence -nostdlib -I ../boot
 CAMLOPT=../boot/ocamlrun ../ocamlopt -nostdlib -I ../stdlib
-COMPFLAGS=-w +33..39 -warn-error A -bin-annot
+COMPFLAGS=-w +33..39 -warn-error A -bin-annot -safe-string
 CAMLYACC=../boot/ocamlyacc
 YACCFLAGS=-v
 CAMLLEX=../boot/ocamlrun ../boot/ocamllex
diff --git a/lex/common.ml b/lex/common.ml
index 13b48fac6d..9b86ba111f 100644
--- a/lex/common.ml
+++ b/lex/common.ml
@@ -47,7 +47,7 @@ let update_tracker tr =
   fprintf tr.oc "# %d \"%s\"\n" (tr.cur_line+1) tr.file;
 ;;
 
-let copy_buffer = String.create 1024
+let copy_buffer = Bytes.create 1024
 
 let copy_chars_unix ic oc start stop =
   let n = ref (stop - start) in
diff --git a/man/ocaml.m b/man/ocaml.m
index b393b771c1..4e041e2176 100644
--- a/man/ocaml.m
+++ b/man/ocaml.m
@@ -157,6 +157,12 @@ Allow arbitrary recursive types during type-checking.  By default,
 only recursive types where the recursion goes through an object type
 are supported.
 .TP
+.B \-safe\-string
+Enforce the separation between types
+.BR string \ and\  bytes ,
+thereby making strings read-only. This will become the default in
+a future version of OCaml.
+.TP
 .B \-short\-paths
 When a type is visible under several module-paths, use the shortest
 one when printing the type's name in inferred interfaces and error and
@@ -177,6 +183,13 @@ constructs). Programs compiled with
 are therefore slightly faster, but unsafe: anything can happen if the program
 accesses an array or string outside of its bounds.
 .TP
+.B \-unsafe\-string
+Identify the types
+.BR string \ and\  bytes ,
+thereby making strings writable. For reasons of backward compatibility,
+this is the default setting for the moment, but this will change in a future
+version of OCaml.
+.TP
 .B \-version
 Print version string and exit.
 .TP
diff --git a/man/ocamlc.m b/man/ocamlc.m
index 1d3c56faa0..6c6174a77b 100644
--- a/man/ocamlc.m
+++ b/man/ocamlc.m
@@ -519,6 +519,12 @@ then the
 .B d
 suffix is supported and gives a debug version of the runtime.
 .TP
+.B \-safe\-string
+Enforce the separation between types
+.BR string \ and\  bytes ,
+thereby making strings read-only. This will become the default in
+a future version of OCaml.
+.TP
 .B \-short\-paths
 When a type is visible under several module-paths, use the shortest
 one when printing the type's name in inferred interfaces and error and
@@ -541,6 +547,13 @@ are therefore
 slightly faster, but unsafe: anything can happen if the program
 accesses an array or string outside of its bounds.
 .TP
+.B \-unsafe\-string
+Identify the types
+.BR string \ and\  bytes ,
+thereby making strings writable. For reasons of backward compatibility,
+this is the default setting for the moment, but this will change in a future
+version of OCaml.
+.TP
 .BI \-use\-runtime \ runtime\-name
 Generate a bytecode executable file that can be executed on the custom
 runtime system
diff --git a/man/ocamlopt.m b/man/ocamlopt.m
index 766d2a4c6b..e951b77f80 100644
--- a/man/ocamlopt.m
+++ b/man/ocamlopt.m
@@ -475,6 +475,12 @@ code for the source file
 is saved in the file
 .IR x .s.
 .TP
+.B \-safe\-string
+Enforce the separation between types
+.BR string \ and\  bytes ,
+thereby making strings read-only. This will become the default in
+a future version of OCaml.
+.TP
 .B \-shared
 Build a plugin (usually .cmxs) that can be dynamically loaded with
 the
@@ -522,6 +528,13 @@ program or continue with an unspecified result instead of raising a
 .B Division_by_zero
 exception.
 .TP
+.B \-unsafe\-string
+Identify the types
+.BR string \ and\  bytes ,
+thereby making strings writable. For reasons of backward compatibility,
+this is the default setting for the moment, but this will change in a future
+version of OCaml.
+.TP
 .B \-v
 Print the version number of the compiler and the location of the
 standard library directory, then exit.
diff --git a/ocamlbuild/Makefile b/ocamlbuild/Makefile
index 54d6283246..085e1a3662 100644
--- a/ocamlbuild/Makefile
+++ b/ocamlbuild/Makefile
@@ -19,7 +19,7 @@ OCAMLOPT  = $(OCAMLRUN) $(ROOTDIR)/ocamlopt -nostdlib -I $(ROOTDIR)/stdlib
 OCAMLDEP  = $(OCAMLRUN) $(ROOTDIR)/tools/ocamldep
 OCAMLLEX  = $(OCAMLRUN) $(ROOTDIR)/boot/ocamllex
 CP        = cp
-COMPFLAGS= -warn-error A -w L -w R -w Z -I ../otherlibs/$(UNIXLIB)
+COMPFLAGS= -warn-error A -w L -w R -w Z -I ../otherlibs/$(UNIXLIB) -safe-string
 LINKFLAGS= -I ../otherlibs/$(UNIXLIB)
 
 PACK_CMO=\
diff --git a/ocamlbuild/Makefile.noboot b/ocamlbuild/Makefile.noboot
index de914e15ec..313e56891c 100644
--- a/ocamlbuild/Makefile.noboot
+++ b/ocamlbuild/Makefile.noboot
@@ -56,7 +56,7 @@ INCLUDES_NODEP=	-I $(OCAMLSRCDIR)/stdlib \
 
 INCLUDES=$(INCLUDES_DEP) $(INCLUDES_NODEP)
 
-COMPFLAGS=$(INCLUDES) -warn-error A
+COMPFLAGS=$(INCLUDES) -warn-error A -safe-string
 LINKFLAGS=$(INCLUDES)
 
 CMOFILES_PACK= 			            \
diff --git a/ocamlbuild/display.ml b/ocamlbuild/display.ml
index 725d351bb6..2e0b1e39ea 100644
--- a/ocamlbuild/display.ml
+++ b/ocamlbuild/display.ml
@@ -51,7 +51,7 @@ type sophisticated_display = {
           ds_columns         : int;                    (** Number of columns in dssplay *)
   mutable ds_jobs            : int;                    (** Number of jobs launched or cached *)
   mutable ds_jobs_cached     : int;                    (** Number of jobs cached *)
-          ds_tagline         : string;                 (** Current tagline *)
+          ds_tagline         : bytes;                  (** Current tagline *)
   mutable ds_seen_tags       : Tags.t;                 (** Tags that we have encountered *)
           ds_pathname_length : int;                    (** How much space for displaying pathnames ? *)
           ds_tld             : tagline_description;    (** Description for the tagline *)
@@ -105,7 +105,7 @@ let uncached = " ";;
 let cache_chars = 1;;
 (* ***)
 (*** create_tagline *)
-let create_tagline description = String.make (List.length description) '-';;
+let create_tagline description = Bytes.make (List.length description) '-';;
 (* ***)
 (*** create *)
 let create
@@ -184,7 +184,7 @@ let print_shortened_pathname length oc u =
       let n = String.length dots in
       let k = length - n in
       output_string oc dots;
-      output oc u (m - k) k;
+      output_substring oc u (m - k) k;
     end
 (* ***)
 (*** Layout
@@ -216,7 +216,7 @@ let redraw_sophisticated ds =
     ds.ds_jobs_cached
     (print_shortened_pathname ds.ds_pathname_length) ds.ds_last_target
     (if ds.ds_last_cached then cached else uncached)
-    ds.ds_tagline
+    (Bytes.to_string ds.ds_tagline)
     ticker;
   fp oc "%a%!" ANSI.clear_to_eol ()
 ;;
@@ -292,17 +292,17 @@ let update_tagline_from_tags ds =
   let tags = ds.ds_last_tags in
   let rec loop i = function
     | [] ->
-        for j = i to String.length tagline - 1 do
-          tagline.[j] <- '-'
+        for j = i to Bytes.length tagline - 1 do
+          Bytes.set tagline j '-'
         done
     | (tag, c) :: rest ->
         if Tags.mem tag tags then
-          tagline.[i] <- Char.uppercase c
+          Bytes.set tagline i (Char.uppercase c)
         else
           if Tags.mem tag ds.ds_seen_tags then
-            tagline.[i] <- Char.lowercase c
+            Bytes.set tagline i (Char.lowercase c)
           else
-            tagline.[i] <- '-';
+            Bytes.set tagline i '-';
         loop (i + 1) rest
   in
   loop 0 ds.ds_tld;
diff --git a/ocamlbuild/my_std.ml b/ocamlbuild/my_std.ml
index e0d2c8a9ca..c283987cc2 100644
--- a/ocamlbuild/my_std.ml
+++ b/ocamlbuild/my_std.ml
@@ -180,14 +180,7 @@ module String = struct
     in loop s 0
 
   let tr patt subst text =
-    let len = length text in
-    let text = copy text in
-    let rec loop pos =
-      if pos < len then begin
-        (if text.[pos] = patt then text.[pos] <- subst);
-        loop (pos + 1)
-      end
-    in loop 0; text
+    String.map (fun c -> if c = patt then subst else c) text
 
   (*** is_prefix : is u a prefix of v ? *)
   let is_prefix u v =
@@ -211,23 +204,23 @@ module String = struct
 
   let rev s =
     let sl = String.length s in
-    let s' = String.create sl in
+    let s' = Bytes.create sl in
     for i = 0 to sl - 1 do
-      s'.[i] <- s.[sl - i - 1]
+      Bytes.set s' i s.[sl - i - 1]
     done;
-    s';;
+    Bytes.to_string s';;
 
   let implode l =
     match l with
     | [] -> ""
     | cs ->
-        let r = create (List.length cs) in
+        let r = Bytes.create (List.length cs) in
         let pos = ref 0 in
         List.iter begin fun c ->
-          unsafe_set r !pos c;
+          Bytes.unsafe_set r !pos c;
           incr pos
         end cs;
-        r
+        Bytes.to_string r
 
   let explode s =
     let sl = String.length s in
@@ -307,16 +300,14 @@ let with_output_file ?(bin=false) x f =
 let read_file x =
   with_input_file ~bin:true x begin fun ic ->
     let len = in_channel_length ic in
-    let buf = String.create len in
-    let () = really_input ic buf 0 len in
-    buf
+    really_input_string ic len
   end
 
 let copy_chan ic oc =
   let m = in_channel_length ic in
   let m = (m lsr 12) lsl 12 in
   let m = max 16384 (min Sys.max_string_length m) in
-  let buf = String.create m in
+  let buf = Bytes.create m in
   let rec loop () =
     let len = input ic buf 0 m in
     if len > 0 then begin
diff --git a/ocamlbuild/my_unix.ml b/ocamlbuild/my_unix.ml
index 43692d3219..fa1c5d45f4 100644
--- a/ocamlbuild/my_unix.ml
+++ b/ocamlbuild/my_unix.ml
@@ -127,13 +127,13 @@ let execute_many ?max_jobs = implem.execute_many ?max_jobs
 
 let run_and_read cmd =
   let bufsiz = 2048 in
-  let buf = String.create bufsiz in
+  let buf = Bytes.create bufsiz in
   let totalbuf = Buffer.create 4096 in
   implem.run_and_open cmd begin fun ic ->
     let rec loop pos =
       let len = input ic buf 0 bufsiz in
       if len > 0 then begin
-        Buffer.add_substring totalbuf buf 0 len;
+        Buffer.add_subbytes totalbuf buf 0 len;
         loop (pos + len)
       end
     in loop 0; Buffer.contents totalbuf
diff --git a/ocamlbuild/ocamlbuild_executor.ml b/ocamlbuild/ocamlbuild_executor.ml
index 53fcad1201..1a95204105 100644
--- a/ocamlbuild/ocamlbuild_executor.ml
+++ b/ocamlbuild/ocamlbuild_executor.ml
@@ -59,7 +59,7 @@ let output_lines prefix oc buffer =
   let m = String.length u in
   let output_line i j =
     output_string oc prefix;
-    output oc u i (j - i);
+    output_substring oc u i (j - i);
     output_char oc '\n'
   in
   let rec loop i =
@@ -190,7 +190,7 @@ let execute
   (* ***)
   (*** do_read *)
   let do_read =
-    let u = String.create 4096 in
+    let u = Bytes.create 4096 in
     fun ?(loop=false) fd job ->
       (*if job.job_dying then
         ()
@@ -199,7 +199,7 @@ let execute
           let rec iteration () =
             let m =
               try
-                read fd u 0 (String.length u)
+                read fd u 0 (Bytes.length u)
               with
               | Unix.Unix_error(_,_,_) -> 0
             in
@@ -210,7 +210,7 @@ let execute
                 terminate job
             else
               begin
-                Buffer.add_substring job.job_buffer u 0 m;
+                Buffer.add_subbytes job.job_buffer u 0 m;
                 if loop then
                   iteration ()
                 else
diff --git a/ocamldoc/Makefile b/ocamldoc/Makefile
index f5e47a59bd..6529ae1e44 100644
--- a/ocamldoc/Makefile
+++ b/ocamldoc/Makefile
@@ -76,7 +76,7 @@ INCLUDES_NODEP=	-I $(OCAMLSRCDIR)/stdlib \
 
 INCLUDES=$(INCLUDES_DEP) $(INCLUDES_NODEP)
 
-COMPFLAGS=$(INCLUDES) -warn-error A
+COMPFLAGS=$(INCLUDES) -warn-error A -safe-string
 LINKFLAGS=$(INCLUDES) -nostdlib
 
 CMOFILES= odoc_config.cmo \
diff --git a/ocamldoc/odoc_analyse.ml b/ocamldoc/odoc_analyse.ml
index 98f73617df..294ca95c5b 100644
--- a/ocamldoc/odoc_analyse.ml
+++ b/ocamldoc/odoc_analyse.ml
@@ -33,10 +33,13 @@ let init_path () =
 
 (** Return the initial environment in which compilation proceeds. *)
 let initial_env () =
+  let initial =
+    if !Clflags.unsafe_string then Env.initial_unsafe_string
+    else Env.initial_safe_string
+  in
   try
-    if !Clflags.nopervasives
-    then Env.initial
-    else Env.open_pers_signature "Pervasives" Env.initial
+    if !Clflags.nopervasives then initial else
+    Env.open_pers_signature "Pervasives" initial
   with Not_found ->
     fatal_error "cannot open pervasives.cmi"
 
diff --git a/ocamldoc/odoc_misc.ml b/ocamldoc/odoc_misc.ml
index c762ade2a4..74b62015a7 100644
--- a/ocamldoc/odoc_misc.ml
+++ b/ocamldoc/odoc_misc.ml
@@ -23,7 +23,7 @@ let no_blanks s =
 let input_file_as_string nom =
   let chanin = open_in_bin nom in
   let len = 1024 in
-  let s = String.create len in
+  let s = Bytes.create len in
   let buf = Buffer.create len in
   let rec iter () =
     try
@@ -32,7 +32,7 @@ let input_file_as_string nom =
         ()
       else
         (
-         Buffer.add_substring buf s 0 n;
+         Buffer.add_subbytes buf s 0 n;
          iter ()
         )
     with
diff --git a/ocamldoc/odoc_texi.ml b/ocamldoc/odoc_texi.ml
index 95354caac8..bb90e0618a 100644
--- a/ocamldoc/odoc_texi.ml
+++ b/ocamldoc/odoc_texi.ml
@@ -42,24 +42,20 @@ let is = function
 
 let pad_to n s =
   let len = String.length s in
-  if len < n
-  then
-    let s' = String.make n ' ' in
-    String.blit s 0 s' 0 len ; s'
-  else s
+  if len < n then s ^ String.make (n - len) ' ' else s
 
 let indent nb_sp s =
   let c = ref 0 in
   let len = pred (String.length s) in
   for i = 0 to len do if s.[i] = '\n' then incr c done ;
-  let s' = String.make (succ len + (succ !c) * nb_sp ) ' ' in
+  let s' = Bytes.make (succ len + (succ !c) * nb_sp ) ' ' in
   c := nb_sp ;
   for i = 0 to len do
-    s'.[!c] <- s.[i] ;
+    Bytes.set s' !c s.[i] ;
     if s.[i] = '\n' then c := !c + nb_sp ;
     incr c
   done ;
-  s'
+  Bytes.to_string s'
 
 type subparts = [
   | `Module of Odoc_info.Module.t_module
@@ -445,8 +441,7 @@ class texi =
     method private soft_fix_linebreaks =
       let re = Str.regexp "\n[ \t]*" in
       fun ind t ->
-        let rep = String.make (succ ind) ' ' in
-        rep.[0] <- '\n' ;
+        let rep = "\n" ^ String.make ind ' ' in
         List.map
           (function
             | Raw s -> Raw (Str.global_replace re rep s)
diff --git a/otherlibs/Makefile.shared b/otherlibs/Makefile.shared
index 6c2fc5d67a..9bed5f7604 100644
--- a/otherlibs/Makefile.shared
+++ b/otherlibs/Makefile.shared
@@ -19,7 +19,7 @@ include $(ROOTDIR)/config/Makefile
 # Compilation options
 CC=$(BYTECC)
 CAMLRUN=$(ROOTDIR)/boot/ocamlrun
-COMPFLAGS=-w +33..39 -warn-error A -bin-annot -g $(EXTRACAMLFLAGS)
+COMPFLAGS=-w +33..39 -warn-error A -bin-annot -g -safe-string $(EXTRACAMLFLAGS)
 MKLIB=$(CAMLRUN) $(ROOTDIR)/tools/ocamlmklib
 
 # Variables to be defined by individual libraries:
diff --git a/otherlibs/bigarray/.depend b/otherlibs/bigarray/.depend
index 4df63a3e32..d705f2022e 100644
--- a/otherlibs/bigarray/.depend
+++ b/otherlibs/bigarray/.depend
@@ -1,21 +1,21 @@
 bigarray_stubs.o: bigarray_stubs.c ../../byterun/alloc.h \
- ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h bigarray.h \
- ../../byterun/config.h ../../byterun/mlvalues.h ../../byterun/custom.h \
- ../../byterun/fail.h ../../byterun/intext.h ../../byterun/io.h \
- ../../byterun/hash.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h ../../byterun/int64_native.h
+  ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h bigarray.h \
+  ../../byterun/config.h ../../byterun/mlvalues.h ../../byterun/custom.h \
+  ../../byterun/fail.h ../../byterun/intext.h ../../byterun/io.h \
+  ../../byterun/hash.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h ../../byterun/int64_native.h
 mmap_unix.o: mmap_unix.c bigarray.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/mlvalues.h ../../byterun/config.h ../../byterun/misc.h \
- ../../byterun/custom.h ../../byterun/mlvalues.h ../../byterun/fail.h \
- ../../byterun/io.h ../../byterun/sys.h ../../byterun/signals.h
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/mlvalues.h ../../byterun/config.h ../../byterun/misc.h \
+  ../../byterun/custom.h ../../byterun/mlvalues.h ../../byterun/fail.h \
+  ../../byterun/io.h ../../byterun/sys.h ../../byterun/signals.h
 mmap_win32.o: mmap_win32.c bigarray.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/mlvalues.h ../../byterun/config.h ../../byterun/misc.h \
- ../../byterun/alloc.h ../../byterun/mlvalues.h ../../byterun/custom.h \
- ../../byterun/fail.h ../../byterun/sys.h ../unix/unixsupport.h
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/mlvalues.h ../../byterun/config.h ../../byterun/misc.h \
+  ../../byterun/alloc.h ../../byterun/mlvalues.h ../../byterun/custom.h \
+  ../../byterun/fail.h ../../byterun/sys.h ../unix/unixsupport.h
 bigarray.cmi :
 bigarray.cmo : bigarray.cmi
 bigarray.cmx : bigarray.cmi
diff --git a/otherlibs/dynlink/Makefile b/otherlibs/dynlink/Makefile
index 15b01921bb..6284a5283e 100644
--- a/otherlibs/dynlink/Makefile
+++ b/otherlibs/dynlink/Makefile
@@ -21,7 +21,8 @@ OCAMLC    = $(OCAMLRUN) $(ROOTDIR)/ocamlc -nostdlib -I $(ROOTDIR)/stdlib
 OCAMLOPT  = $(OCAMLRUN) $(ROOTDIR)/ocamlopt -nostdlib -I $(ROOTDIR)/stdlib
 
 INCLUDES=-I ../../utils -I ../../typing -I ../../bytecomp -I ../../asmcomp
-COMPFLAGS=-w +33..39 -warn-error A -bin-annot -I ../../stdlib $(INCLUDES)
+COMPFLAGS=-w +33..39 -warn-error A -bin-annot -safe-string \
+          -I ../../stdlib $(INCLUDES)
 
 OBJS=dynlinkaux.cmo dynlink.cmo
 
diff --git a/otherlibs/dynlink/dynlink.ml b/otherlibs/dynlink/dynlink.ml
index fee98f1c1b..15febc3c89 100644
--- a/otherlibs/dynlink/dynlink.ml
+++ b/otherlibs/dynlink/dynlink.ml
@@ -152,7 +152,9 @@ let digest_interface unit loadpath =
       raise (Error(File_not_found shortname)) in
   let ic = open_in_bin filename in
   try
-    let buffer = Misc.input_bytes ic (String.length Config.cmi_magic_number) in
+    let buffer =
+      really_input_string ic (String.length Config.cmi_magic_number)
+    in
     if buffer <> Config.cmi_magic_number then begin
       close_in ic;
       raise(Error(Corrupted_interface filename))
@@ -189,7 +191,7 @@ let check_unsafe_module cu =
 
 (* Load in-core and execute a bytecode object file *)
 
-external register_code_fragment: string -> int -> string -> unit
+external register_code_fragment: bytes -> int -> string -> unit
                                = "caml_register_code_fragment"
 
 let load_compunit ic file_name file_digest compunit =
@@ -199,14 +201,14 @@ let load_compunit ic file_name file_digest compunit =
   let code_size = compunit.cu_codesize + 8 in
   let code = Meta.static_alloc code_size in
   unsafe_really_input ic code 0 compunit.cu_codesize;
-  String.unsafe_set code compunit.cu_codesize (Char.chr Opcodes.opRETURN);
-  String.unsafe_set code (compunit.cu_codesize + 1) '\000';
-  String.unsafe_set code (compunit.cu_codesize + 2) '\000';
-  String.unsafe_set code (compunit.cu_codesize + 3) '\000';
-  String.unsafe_set code (compunit.cu_codesize + 4) '\001';
-  String.unsafe_set code (compunit.cu_codesize + 5) '\000';
-  String.unsafe_set code (compunit.cu_codesize + 6) '\000';
-  String.unsafe_set code (compunit.cu_codesize + 7) '\000';
+  Bytes.unsafe_set code compunit.cu_codesize (Char.chr Opcodes.opRETURN);
+  Bytes.unsafe_set code (compunit.cu_codesize + 1) '\000';
+  Bytes.unsafe_set code (compunit.cu_codesize + 2) '\000';
+  Bytes.unsafe_set code (compunit.cu_codesize + 3) '\000';
+  Bytes.unsafe_set code (compunit.cu_codesize + 4) '\001';
+  Bytes.unsafe_set code (compunit.cu_codesize + 5) '\000';
+  Bytes.unsafe_set code (compunit.cu_codesize + 6) '\000';
+  Bytes.unsafe_set code (compunit.cu_codesize + 7) '\000';
   let initial_symtable = Symtable.current_state() in
   begin try
     Symtable.patch_object code compunit.cu_reloc;
@@ -242,7 +244,7 @@ let loadfile file_name =
   seek_in ic 0;
   try
     let buffer =
-      try Misc.input_bytes ic (String.length Config.cmo_magic_number)
+      try really_input_string ic (String.length Config.cmo_magic_number)
       with End_of_file -> raise (Error (Not_a_bytecode_file file_name))
     in
     if buffer = Config.cmo_magic_number then begin
diff --git a/otherlibs/dynlink/natdynlink.ml b/otherlibs/dynlink/natdynlink.ml
index fd06d7c70c..0ae24fa681 100644
--- a/otherlibs/dynlink/natdynlink.ml
+++ b/otherlibs/dynlink/natdynlink.ml
@@ -15,9 +15,9 @@
 
 type handle
 
-external ndl_open: string -> bool -> handle * string = "caml_natdynlink_open"
+external ndl_open: string -> bool -> handle * bytes = "caml_natdynlink_open"
 external ndl_run: handle -> string -> unit = "caml_natdynlink_run"
-external ndl_getmap: unit -> string = "caml_natdynlink_getmap"
+external ndl_getmap: unit -> bytes = "caml_natdynlink_getmap"
 external ndl_globals_inited: unit -> int = "caml_natdynlink_globals_inited"
 
 type linking_error =
@@ -59,7 +59,7 @@ let read_file filename priv =
   if Obj.tag (Obj.repr res) = Obj.string_tag
   then raise (Error (Cannot_open_dll (Obj.magic res)));
 
-  let header : dynheader = Marshal.from_string data 0 in
+  let header : dynheader = Marshal.from_bytes data 0 in
   if header.dynu_magic <> cmxs_magic_number
   then raise(Error(Not_a_bytecode_file dll));
   (dll, handle, header.dynu_units)
@@ -92,7 +92,7 @@ let inited = ref false
 
 let default_available_units () =
   let map : (string*Digest.t*Digest.t*string list) list =
-    Marshal.from_string (ndl_getmap ()) 0 in
+    Marshal.from_bytes (ndl_getmap ()) 0 in
   let exe = Sys.executable_name in
   let rank = ref 0 in
   global_state :=
diff --git a/otherlibs/graph/.depend b/otherlibs/graph/.depend
index b4b531d43a..ab9faa619a 100644
--- a/otherlibs/graph/.depend
+++ b/otherlibs/graph/.depend
@@ -1,63 +1,103 @@
-color.o: color.c libgraph.h ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h
-draw.o: draw.c libgraph.h ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h
-dump_img.o: dump_img.c libgraph.h ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h image.h ../../byterun/alloc.h \
- ../../byterun/mlvalues.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h
-events.o: events.c libgraph.h ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/signals.h
-fill.o: fill.c libgraph.h ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h
-image.o: image.c libgraph.h ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h image.h ../../byterun/alloc.h \
- ../../byterun/mlvalues.h ../../byterun/custom.h
-make_img.o: make_img.c libgraph.h ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h image.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h
-open.o: open.c libgraph.h ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/callback.h ../../byterun/fail.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h
-point_col.o: point_col.c libgraph.h ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h
-sound.o: sound.c libgraph.h ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h
-subwindow.o: subwindow.c libgraph.h ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h
-text.o: text.c libgraph.h ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h
+color.o: color.c libgraph.h \
+  \
+  \
+  \
+  ../../byterun/mlvalues.h ../../byterun/compatibility.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h \
+ 
+draw.o: draw.c libgraph.h \
+  \
+  \
+  \
+  ../../byterun/mlvalues.h ../../byterun/compatibility.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h
+dump_img.o: dump_img.c libgraph.h \
+  \
+  \
+  \
+  ../../byterun/mlvalues.h ../../byterun/compatibility.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h image.h \
+  ../../byterun/alloc.h ../../byterun/mlvalues.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h
+events.o: events.c libgraph.h \
+  \
+  \
+  \
+  ../../byterun/mlvalues.h ../../byterun/compatibility.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h ../../byterun/signals.h
+fill.o: fill.c libgraph.h \
+  \
+  \
+  \
+  ../../byterun/mlvalues.h ../../byterun/compatibility.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h
+image.o: image.c libgraph.h \
+  \
+  \
+  \
+  ../../byterun/mlvalues.h ../../byterun/compatibility.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h image.h \
+  ../../byterun/alloc.h ../../byterun/mlvalues.h ../../byterun/custom.h
+make_img.o: make_img.c libgraph.h \
+  \
+  \
+  \
+  ../../byterun/mlvalues.h ../../byterun/compatibility.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h image.h \
+  ../../byterun/memory.h ../../byterun/gc.h ../../byterun/mlvalues.h \
+  ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h
+open.o: open.c libgraph.h \
+  \
+  \
+  \
+  ../../byterun/mlvalues.h ../../byterun/compatibility.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h ../../byterun/callback.h ../../byterun/fail.h \
+  ../../byterun/memory.h ../../byterun/gc.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h
+point_col.o: point_col.c libgraph.h \
+  \
+  \
+  \
+  ../../byterun/mlvalues.h ../../byterun/compatibility.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h
+sound.o: sound.c libgraph.h \
+  \
+  \
+  \
+  ../../byterun/mlvalues.h ../../byterun/compatibility.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h
+subwindow.o: subwindow.c libgraph.h \
+  \
+  \
+  \
+  ../../byterun/mlvalues.h ../../byterun/compatibility.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h
+text.o: text.c libgraph.h \
+  \
+  \
+  \
+  ../../byterun/mlvalues.h ../../byterun/compatibility.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h
 graphics.cmi :
 graphicsX11.cmi :
 graphics.cmo : graphics.cmi
diff --git a/otherlibs/num/.depend b/otherlibs/num/.depend
index 32d691cc80..51b180f5d8 100644
--- a/otherlibs/num/.depend
+++ b/otherlibs/num/.depend
@@ -1,6 +1,6 @@
 bng.o: bng.c bng.h ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/compatibility.h bng_amd64.c \
- bng_digit.c
+  ../../byterun/../config/s.h ../../byterun/compatibility.h bng_amd64.c \
+  bng_digit.c
 bng_amd64.o: bng_amd64.c
 bng_arm64.o: bng_arm64.c
 bng_digit.o: bng_digit.c
@@ -8,14 +8,14 @@ bng_ia32.o: bng_ia32.c
 bng_ppc.o: bng_ppc.c
 bng_sparc.o: bng_sparc.c
 nat_stubs.o: nat_stubs.c ../../byterun/alloc.h \
- ../../byterun/compatibility.h ../../byterun/misc.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/config.h ../../byterun/custom.h ../../byterun/intext.h \
- ../../byterun/io.h ../../byterun/fail.h ../../byterun/hash.h \
- ../../byterun/memory.h ../../byterun/gc.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h \
- ../../byterun/mlvalues.h bng.h nat.h
+  ../../byterun/compatibility.h ../../byterun/misc.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/config.h ../../byterun/custom.h ../../byterun/intext.h \
+  ../../byterun/io.h ../../byterun/fail.h ../../byterun/hash.h \
+  ../../byterun/memory.h ../../byterun/gc.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h \
+  ../../byterun/mlvalues.h bng.h nat.h
 arith_flags.cmi :
 arith_status.cmi :
 big_int.cmi : nat.cmi
diff --git a/otherlibs/num/big_int.ml b/otherlibs/num/big_int.ml
index 939bbfb8ee..847d158324 100644
--- a/otherlibs/num/big_int.ml
+++ b/otherlibs/num/big_int.ml
@@ -625,15 +625,15 @@ let square_big_int bi =
    else s <- the round number and the result_int is false *)
 let round_futur_last_digit s off_set length =
  let l = pred (length + off_set) in
-  if Char.code(String.get s l) >= Char.code '5'
+  if Char.code(Bytes.get s l) >= Char.code '5'
     then
      let rec round_rec l =
        if l < off_set then true else begin
-         let current_char = String.get s l in
+         let current_char = Bytes.get s l in
          if current_char = '9' then
-           (String.set s l '0'; round_rec (pred l))
+           (Bytes.set s l '0'; round_rec (pred l))
          else
-           (String.set s l (Char.chr (succ (Char.code current_char)));
+           (Bytes.set s l (Char.chr (succ (Char.code current_char)));
             false)
        end
      in round_rec (pred l)
@@ -652,17 +652,19 @@ let approx_big_int prec bi =
                                       (big_int_of_string "963295986"))
                         (big_int_of_string "100000000")))) in
   let s =
-    string_of_big_int (div_big_int bi (power_int_positive_int 10 n)) in
+    Bytes.unsafe_of_string
+      (string_of_big_int (div_big_int bi (power_int_positive_int 10 n)))
+  in
   let (sign, off, len) =
-    if String.get s 0 = '-'
+    if Bytes.get s 0 = '-'
        then ("-", 1, succ prec)
        else ("", 0, prec) in
   if (round_futur_last_digit s off (succ prec))
        then (sign^"1."^(String.make prec '0')^"e"^
-             (string_of_int (n + 1 - off + String.length s)))
-       else (sign^(String.sub s off 1)^"."^
-             (String.sub s (succ off) (pred prec))
-             ^"e"^(string_of_int (n - succ off + String.length s)))
+             (string_of_int (n + 1 - off + Bytes.length s)))
+       else (sign^(Bytes.sub_string s off 1)^"."^
+             (Bytes.sub_string s (succ off) (pred prec))
+             ^"e"^(string_of_int (n - succ off + Bytes.length s)))
 
 (* Logical operations *)
 
diff --git a/otherlibs/num/big_int.mli b/otherlibs/num/big_int.mli
index 276108f902..738730a79a 100644
--- a/otherlibs/num/big_int.mli
+++ b/otherlibs/num/big_int.mli
@@ -187,5 +187,5 @@ val nat_of_big_int : big_int -> nat
 val big_int_of_nat : nat -> big_int
 val base_power_big_int: int -> int -> big_int -> big_int
 val sys_big_int_of_string: string -> int -> int -> big_int
-val round_futur_last_digit : string -> int -> int -> bool
+val round_futur_last_digit : bytes -> int -> int -> bool
 val approx_big_int: int -> big_int -> string
diff --git a/otherlibs/num/nat.ml b/otherlibs/num/nat.ml
index 59f57ee7d8..90cb471c1b 100644
--- a/otherlibs/num/nat.ml
+++ b/otherlibs/num/nat.ml
@@ -282,18 +282,15 @@ let raw_string_of_digit nat off =
        and s1 = string_of_int (nth_digit_nat a_1 0) in
        let len = String.length s1 in
        if leading_digits < 10 then begin
-            let result = String.make (max_superscript_10_power_in_int+1) '0' in
-            String.set result 0
-                         (Char.chr (48 + leading_digits));
-            String.blit s1 0
-                 result (String.length result - len) len;
-            result
+            let result = Bytes.make (max_superscript_10_power_in_int+1) '0' in
+            Bytes.set result 0 (Char.chr (48 + leading_digits));
+            String.blit s1 0 result (Bytes.length result - len) len;
+            Bytes.to_string result
        end else begin
-            let result = String.make (max_superscript_10_power_in_int+2) '0' in
+            let result = Bytes.make (max_superscript_10_power_in_int+2) '0' in
             String.blit (string_of_int leading_digits) 0 result 0 2;
-            String.blit s1 0
-                 result (String.length result - len) len;
-            result
+            String.blit s1 0 result (Bytes.length result - len) len;
+            Bytes.to_string result
        end
   end
 
@@ -344,7 +341,7 @@ let int_to_string int s pos_ref base times =
   let i = ref int
   and j = ref times in
      while ((!i != 0) || (!j != 0)) && (!pos_ref != -1) do
-        String.set s !pos_ref (String.get digits (!i mod base));
+        Bytes.set s !pos_ref (String.get digits (!i mod base));
         decr pos_ref;
         decr j;
         i := !i / base
@@ -466,7 +463,7 @@ let unadjusted_string_of_nat nat off len_nat =
          if len > biggest_int / (succ pmax)
             then failwith "number too long"
             else let len_s = (succ pmax) * len in
-                 let s = String.make len_s '0'
+                 let s = Bytes.make len_s '0'
                  and pos_ref = ref len_s in
                    len_copy := pred !len_copy;
                    blit_nat copy1 0 nat off len;
@@ -488,7 +485,7 @@ let unadjusted_string_of_nat nat off len_nat =
                       blit_nat copy1 0 copy2 0 !len_copy;
                       set_digit_nat copy1 !len_copy 0
                    done;
-                   s
+                   Bytes.unsafe_to_string s
 
 let string_of_nat nat =
   let s = unadjusted_string_of_nat nat 0 (length_nat nat)
diff --git a/otherlibs/num/ratio.ml b/otherlibs/num/ratio.ml
index fe0170f299..5bb04b6474 100644
--- a/otherlibs/num/ratio.ml
+++ b/otherlibs/num/ratio.ml
@@ -438,7 +438,8 @@ let approx_ratio_fix n r =
                    r.denominator)) in
        (* Round up and add 1 in front if needed *)
        let s2 =
-         if round_futur_last_digit s1 0 (String.length s1)
+         if round_futur_last_digit (Bytes.unsafe_of_string s1) 0
+                                   (String.length s1)
          then "1" ^ s1
          else s1 in
        let l2 = String.length s2 - 1 in
@@ -447,18 +448,18 @@ let approx_ratio_fix n r =
             if s2 without last digit is      yy with <= n digits:
                <sign> 0 . 0yy *)
        if l2 > n then begin
-         let s = String.make (l2 + 2) '0' in
-         String.set s 0  (if sign_r = -1 then '-' else '+');
+         let s = Bytes.make (l2 + 2) '0' in
+         Bytes.set s 0  (if sign_r = -1 then '-' else '+');
          String.blit s2 0 s 1 (l2 - n);
-         String.set s (l2 - n + 1) '.';
+         Bytes.set s (l2 - n + 1) '.';
          String.blit s2 (l2 - n) s (l2 - n + 2) n;
-         s
+         Bytes.unsafe_to_string s
        end else begin
-         let s = String.make (n + 3) '0' in
-         String.set s 0  (if sign_r = -1 then '-' else '+');
-         String.set s 2 '.';
+         let s = Bytes.make (n + 3) '0' in
+         Bytes.set s 0  (if sign_r = -1 then '-' else '+');
+         Bytes.set s 2 '.';
          String.blit s2 0 s (n + 3 - l2) l2;
-         s
+         Bytes.unsafe_to_string s
        end
      end else begin
        (* Dubious; what is this code supposed to do? *)
@@ -468,10 +469,10 @@ let approx_ratio_fix n r =
                     (base_power_big_int
                       10 (-n) r.denominator)) in
        let len = succ (String.length s) in
-       let s' = String.make len '0' in
-        String.set s' 0 (if sign_r = -1 then '-' else '+');
+       let s' = Bytes.make len '0' in
+        Bytes.set s' 0 (if sign_r = -1 then '-' else '+');
         String.blit s 0 s' 1 (pred len);
-        s'
+        Bytes.unsafe_to_string s'
      end
 
 (* Number of digits of the decimal representation of an int *)
@@ -488,11 +489,8 @@ let approx_ratio_exp n r =
  else
   let sign_r = sign_ratio r
   and i = ref (n + 3) in
-   if sign_r = 0
-     then
-      let s = String.make (n + 5) '0' in
-       (String.blit "+0." 0 s 0 3);
-       (String.blit "e0" 0 s !i 2); s
+   if sign_r = 0 then
+     String.concat "" ["+0."; String.make n '0'; "e0"]
    else
      let msd = msd_ratio (abs_ratio r) in
      let k = n - msd in
@@ -508,28 +506,29 @@ let approx_ratio_exp n r =
                                 10 k (abs_big_int r.numerator))
                                r.denominator) in
        string_of_nat nat) in
-     if (round_futur_last_digit s 0 (String.length s))
+     if round_futur_last_digit (Bytes.unsafe_of_string s) 0
+                               (String.length s)
       then
        let m = num_decimal_digits_int (succ msd) in
-       let str = String.make (n + m + 4) '0' in
+       let str = Bytes.make (n + m + 4) '0' in
          (String.blit (if sign_r = -1 then "-1." else "+1.") 0 str 0 3);
-         String.set str !i ('e');
+         Bytes.set str !i ('e');
          incr i;
          (if m = 0
-          then String.set str !i '0'
+          then Bytes.set str !i '0'
           else String.blit (string_of_int (succ msd)) 0 str !i m);
-         str
+         Bytes.unsafe_to_string str
      else
       let m = num_decimal_digits_int (succ msd)
       and p = n + 3 in
-      let str = String.make (succ (m + p)) '0' in
+      let str = Bytes.make (succ (m + p)) '0' in
         (String.blit (if sign_r = -1 then "-0." else "+0.") 0 str 0 3);
         (String.blit s 0 str 3 n);
-        String.set str p 'e';
+        Bytes.set str p 'e';
         (if m = 0
-          then String.set str (succ p) '0'
+          then Bytes.set str (succ p) '0'
           else (String.blit (string_of_int (succ msd)) 0 str (succ p) m));
-        str
+        Bytes.unsafe_to_string str
 
 (* String approximation of a rational with a fixed number of significant *)
 (* digits printed                                                        *)
diff --git a/otherlibs/str/.depend b/otherlibs/str/.depend
index b0ff35895b..5be8377c2d 100644
--- a/otherlibs/str/.depend
+++ b/otherlibs/str/.depend
@@ -1,9 +1,9 @@
 strstubs.o: strstubs.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/memory.h ../../byterun/gc.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h ../../byterun/fail.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
+  ../../byterun/memory.h ../../byterun/gc.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h ../../byterun/fail.h
 str.cmi :
 str.cmo : str.cmi
 str.cmx : str.cmi
diff --git a/otherlibs/str/str.ml b/otherlibs/str/str.ml
index b9b8c1536d..ffaea89ba4 100644
--- a/otherlibs/str/str.ml
+++ b/otherlibs/str/str.ml
@@ -25,16 +25,18 @@ let last_chars s n = String.sub s (String.length s - n) n
 
 module Charset =
   struct
-    type t = string (* of length 32 *)
+    type t = bytes (* of length 32 *)
 
-    (*let empty = String.make 32 '\000'*)
-    let full = String.make 32 '\255'
+    (*let empty = Bytes.make 32 '\000'*)
+    let full = Bytes.make 32 '\255'
 
-    let make_empty () = String.make 32 '\000'
+    let make_empty () = Bytes.make 32 '\000'
 
     let add s c =
       let i = Char.code c in
-      s.[i lsr 3] <- Char.chr(Char.code s.[i lsr 3] lor (1 lsl (i land 7)))
+      Bytes.set s (i lsr 3)
+                (Char.chr (Char.code (Bytes.get s (i lsr 3))
+                           lor (1 lsl (i land 7))))
 
     let add_range s c1 c2 =
       for i = Char.code c1 to Char.code c2 do add s (Char.chr i) done
@@ -46,23 +48,26 @@ module Charset =
       let s = make_empty () in add_range s c1 c2; s
     *)
     let complement s =
-      let r = String.create 32 in
+      let r = Bytes.create 32 in
       for i = 0 to 31 do
-        r.[i] <- Char.chr(Char.code s.[i] lxor 0xFF)
+        Bytes.set r i (Char.chr(Char.code (Bytes.get s i) lxor 0xFF))
       done;
       r
 
     let union s1 s2 =
-      let r = String.create 32 in
+      let r = Bytes.create 32 in
       for i = 0 to 31 do
-        r.[i] <- Char.chr(Char.code s1.[i] lor Char.code s2.[i])
+        Bytes.set r i (Char.chr(Char.code (Bytes.get s1 i)
+                       lor Char.code (Bytes.get s2 i)))
       done;
       r
 
     let disjoint s1 s2 =
       try
         for i = 0 to 31 do
-          if Char.code s1.[i] land Char.code s2.[i] <> 0 then raise Exit
+          if Char.code (Bytes.get s1 i) land Char.code (Bytes.get s2 i)
+             <> 0
+          then raise Exit
         done;
         true
       with Exit ->
@@ -70,7 +75,7 @@ module Charset =
 
     let iter fn s =
       for i = 0 to 31 do
-        let c = Char.code s.[i] in
+        let c = Char.code (Bytes.get s i) in
         if c <> 0 then
           for j = 0 to 7 do
             if c land (1 lsl j) <> 0 then fn (Char.chr ((i lsl 3) + j))
@@ -78,8 +83,8 @@ module Charset =
       done
 
     let expand s =
-      let r = String.make 256 '\000' in
-      iter (fun c -> r.[Char.code c] <- '\001') s;
+      let r = Bytes.make 256 '\000' in
+      iter (fun c -> Bytes.set r (Char.code c) '\001') s;
       r
 
     let fold_case s =
@@ -201,14 +206,14 @@ let charclass_of_regexp fold_case re =
     | CharClass(cl, compl) -> (cl, compl)
     | _ -> assert false in
   let cl2 = if fold_case then Charset.fold_case cl1 else cl1 in
-  if compl then Charset.complement cl2 else cl2
+  Bytes.to_string (if compl then Charset.complement cl2 else cl2)
 
 (* The case fold table: maps characters to their lowercase equivalent *)
 
 let fold_case_table =
-  let t = String.create 256 in
-  for i = 0 to 255 do t.[i] <- Char.lowercase(Char.chr i) done;
-  t
+  let t = Bytes.create 256 in
+  for i = 0 to 255 do Bytes.set t i (Char.lowercase(Char.chr i)) done;
+  Bytes.to_string t
 
 module StringMap =
   Map.Make(struct type t = string let compare (x:t) y = compare x y end)
@@ -292,7 +297,7 @@ let compile fold_case re =
   | CharClass(cl, compl) ->
       let cl1 = if fold_case then Charset.fold_case cl else cl in
       let cl2 = if compl then Charset.complement cl1 else cl1 in
-      emit_instr op_CHARCLASS (cpool_index cl2)
+      emit_instr op_CHARCLASS (cpool_index (Bytes.to_string cl2))
   | Seq rl ->
       emit_seq_code rl
   | Alt(r1, r2) ->
@@ -412,7 +417,7 @@ let compile fold_case re =
   let start_pos =
     if start = Charset.full
     then -1
-    else cpool_index (Charset.expand start') in
+    else cpool_index (Bytes.to_string (Charset.expand start')) in
   let constantpool = Array.make !cpoolpos "" in
   StringMap.iter (fun str idx -> constantpool.(idx) <- str) !cpool;
   { prog = Array.sub !prog 0 !progpos;
@@ -553,16 +558,19 @@ let regexp_case_fold e = compile true (parse e)
 
 let quote s =
   let len = String.length s in
-  let buf = String.create (2 * len) in
+  let buf = Bytes.create (2 * len) in
   let pos = ref 0 in
   for i = 0 to len - 1 do
     match s.[i] with
       '[' | ']' | '*' | '.' | '\\' | '?' | '+' | '^' | '$' as c ->
-        buf.[!pos] <- '\\'; buf.[!pos + 1] <- c; pos := !pos + 2
+        Bytes.set buf !pos '\\';
+        Bytes.set buf (!pos + 1) c;
+        pos := !pos + 2
     | c ->
-        buf.[!pos] <- c; pos := !pos + 1
+        Bytes.set buf !pos c;
+        pos := !pos + 1
   done;
-  String.sub buf 0 !pos
+  Bytes.sub_string buf 0 !pos
 
 let regexp_string s = compile false (String s)
 
diff --git a/otherlibs/systhreads/.depend b/otherlibs/systhreads/.depend
index 93b01d6876..85add2e592 100644
--- a/otherlibs/systhreads/.depend
+++ b/otherlibs/systhreads/.depend
@@ -1,14 +1,14 @@
 st_stubs.o: st_stubs.c ../../byterun/alloc.h \
- ../../byterun/compatibility.h ../../byterun/misc.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/backtrace.h ../../byterun/callback.h \
- ../../byterun/custom.h ../../byterun/fail.h ../../byterun/io.h \
- ../../byterun/memory.h ../../byterun/gc.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h ../../byterun/misc.h \
- ../../byterun/mlvalues.h ../../byterun/printexc.h ../../byterun/roots.h \
- ../../byterun/memory.h ../../byterun/signals.h ../../byterun/stacks.h \
- ../../byterun/sys.h threads.h st_posix.h
+  ../../byterun/compatibility.h ../../byterun/misc.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/backtrace.h ../../byterun/callback.h \
+  ../../byterun/custom.h ../../byterun/fail.h ../../byterun/io.h \
+  ../../byterun/memory.h ../../byterun/gc.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h ../../byterun/misc.h \
+  ../../byterun/mlvalues.h ../../byterun/printexc.h ../../byterun/roots.h \
+  ../../byterun/memory.h ../../byterun/signals.h ../../byterun/stacks.h \
+  ../../byterun/sys.h threads.h st_posix.h
 condition.cmi : mutex.cmi
 event.cmi :
 mutex.cmi :
diff --git a/otherlibs/systhreads/Makefile b/otherlibs/systhreads/Makefile
index a34bd4b879..a08bf34b43 100644
--- a/otherlibs/systhreads/Makefile
+++ b/otherlibs/systhreads/Makefile
@@ -19,7 +19,7 @@ CAMLC=$(ROOTDIR)/boot/ocamlrun $(ROOTDIR)/ocamlc -nostdlib \
 CAMLOPT=$(ROOTDIR)/boot/ocamlrun $(ROOTDIR)/ocamlopt -nostdlib \
         -I $(ROOTDIR)/stdlib -I $(ROOTDIR)/otherlibs/unix
 MKLIB=../../boot/ocamlrun ../../tools/ocamlmklib
-COMPFLAGS=-w +33..39 -warn-error A -g -bin-annot
+COMPFLAGS=-w +33..39 -warn-error A -g -bin-annot -safe-string
 
 BYTECODE_C_OBJS=st_stubs_b.o
 NATIVECODE_C_OBJS=st_stubs_n.o
diff --git a/otherlibs/systhreads/threadUnix.ml b/otherlibs/systhreads/threadUnix.ml
index 335afcb09e..c18f75bb47 100644
--- a/otherlibs/systhreads/threadUnix.ml
+++ b/otherlibs/systhreads/threadUnix.ml
@@ -26,6 +26,7 @@ let waitpid = Unix.waitpid
 let system = Unix.system
 let read = Unix.read
 let write = Unix.write
+let write_substring = Unix.write_substring
 let select = Unix.select
 
 let timed_read fd buff ofs len timeout =
@@ -38,6 +39,9 @@ let timed_write fd buff ofs len timeout =
   then Unix.write fd buff ofs len
   else raise (Unix_error(ETIMEDOUT, "timed_write", ""))
 
+let timed_write_substring fd buff ofs len timeout =
+  timed_write fd (Bytes.unsafe_of_string buff) ofs len timeout
+
 let pipe = Unix.pipe
 
 let open_process_in = Unix.open_process_in
@@ -52,6 +56,8 @@ external connect : file_descr -> sockaddr -> unit = "unix_connect"
 let recv = Unix.recv
 let recvfrom = Unix.recvfrom
 let send = Unix.send
+let send_substring = Unix.send_substring
 let sendto = Unix.sendto
+let sendto_substring = Unix.sendto_substring
 
 let open_connection = Unix.open_connection
diff --git a/otherlibs/systhreads/threadUnix.mli b/otherlibs/systhreads/threadUnix.mli
index 63d27335f5..cac796b925 100644
--- a/otherlibs/systhreads/threadUnix.mli
+++ b/otherlibs/systhreads/threadUnix.mli
@@ -30,24 +30,29 @@ val system : string -> Unix.process_status
 
 (** {6 Basic input/output} *)
 
-val read : Unix.file_descr -> string -> int -> int -> int
-val write : Unix.file_descr -> string -> int -> int -> int
+val read : Unix.file_descr -> bytes -> int -> int -> int
+val write : Unix.file_descr -> bytes -> int -> int -> int
+val write_substring : Unix.file_descr -> string -> int -> int -> int
 
 (** {6 Input/output with timeout} *)
 
 val timed_read :
       Unix.file_descr ->
-      string -> int -> int -> float -> int
+      bytes -> int -> int -> float -> int
 (** See {!ThreadUnix.timed_write}. *)
 
 val timed_write :
       Unix.file_descr ->
-      string -> int -> int -> float -> int
+      bytes -> int -> int -> float -> int
 (** Behave as {!ThreadUnix.read} and {!ThreadUnix.write}, except that
    [Unix_error(ETIMEDOUT,_,_)] is raised if no data is
    available for reading or ready for writing after [d] seconds.
    The delay [d] is given in the fifth argument, in seconds. *)
 
+val timed_write_substring :
+      Unix.file_descr -> string -> int -> int -> float -> int
+(** See {!ThreadUnix.timed_write}. *)
+
 (** {6 Polling} *)
 
 val select :
@@ -72,12 +77,16 @@ val socket : Unix.socket_domain ->
              Unix.socket_type -> int -> Unix.file_descr
 val accept : Unix.file_descr -> Unix.file_descr * Unix.sockaddr
 val connect : Unix.file_descr -> Unix.sockaddr -> unit
-val recv : Unix.file_descr -> string ->
+val recv : Unix.file_descr -> bytes ->
            int -> int -> Unix.msg_flag list -> int
-val recvfrom : Unix.file_descr -> string -> int -> int ->
+val recvfrom : Unix.file_descr -> bytes -> int -> int ->
                Unix.msg_flag list -> int * Unix.sockaddr
-val send : Unix.file_descr -> string -> int -> int ->
+val send : Unix.file_descr -> bytes -> int -> int ->
            Unix.msg_flag list -> int
-val sendto : Unix.file_descr -> string -> int -> int ->
+val send_substring : Unix.file_descr -> string -> int -> int ->
+           Unix.msg_flag list -> int
+val sendto : Unix.file_descr -> bytes -> int -> int ->
+             Unix.msg_flag list -> Unix.sockaddr -> int
+val sendto_substring : Unix.file_descr -> string -> int -> int ->
              Unix.msg_flag list -> Unix.sockaddr -> int
 val open_connection : Unix.sockaddr -> in_channel * out_channel
diff --git a/otherlibs/threads/.depend b/otherlibs/threads/.depend
index 091feb6394..bc03050be3 100644
--- a/otherlibs/threads/.depend
+++ b/otherlibs/threads/.depend
@@ -1,14 +1,14 @@
 scheduler.o: scheduler.c ../../byterun/alloc.h \
- ../../byterun/compatibility.h ../../byterun/misc.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/backtrace.h ../../byterun/callback.h \
- ../../byterun/config.h ../../byterun/fail.h ../../byterun/io.h \
- ../../byterun/memory.h ../../byterun/gc.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h ../../byterun/misc.h \
- ../../byterun/mlvalues.h ../../byterun/printexc.h ../../byterun/roots.h \
- ../../byterun/memory.h ../../byterun/signals.h ../../byterun/stacks.h \
- ../../byterun/sys.h
+  ../../byterun/compatibility.h ../../byterun/misc.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/backtrace.h ../../byterun/callback.h \
+  ../../byterun/config.h ../../byterun/fail.h ../../byterun/io.h \
+  ../../byterun/memory.h ../../byterun/gc.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h ../../byterun/misc.h \
+  ../../byterun/mlvalues.h ../../byterun/printexc.h ../../byterun/roots.h \
+  ../../byterun/memory.h ../../byterun/signals.h ../../byterun/stacks.h \
+  ../../byterun/sys.h
 condition.cmi : mutex.cmi
 event.cmi :
 marshal.cmi :
diff --git a/otherlibs/threads/Makefile b/otherlibs/threads/Makefile
index 5c4be281da..e2b2cb00c2 100644
--- a/otherlibs/threads/Makefile
+++ b/otherlibs/threads/Makefile
@@ -19,7 +19,7 @@ ROOTDIR=../..
 CAMLC=$(ROOTDIR)/boot/ocamlrun $(ROOTDIR)/ocamlc -nostdlib \
       -I $(ROOTDIR)/stdlib -I $(ROOTDIR)/otherlibs/unix
 MKLIB=../../boot/ocamlrun ../../tools/ocamlmklib
-COMPFLAGS=-w +33..39 -warn-error A -bin-annot
+COMPFLAGS=-w +33..39 -warn-error A -bin-annot -safe-string
 
 C_OBJS=scheduler.o
 
diff --git a/otherlibs/threads/marshal.ml b/otherlibs/threads/marshal.ml
index c71ca83d08..005e964372 100644
--- a/otherlibs/threads/marshal.ml
+++ b/otherlibs/threads/marshal.ml
@@ -16,6 +16,9 @@ type extern_flags =
   | Closures
   | Compat_32
 
+external to_bytes: 'a -> extern_flags list -> bytes
+    = "caml_output_value_to_string"
+
 external to_string: 'a -> extern_flags list -> string
     = "caml_output_value_to_string"
 
@@ -23,35 +26,34 @@ let to_channel chan v flags =
   output_string chan (to_string v flags)
 
 external to_buffer_unsafe:
-      string -> int -> int -> 'a -> extern_flags list -> int
+      bytes -> int -> int -> 'a -> extern_flags list -> int
     = "caml_output_value_to_buffer"
 
 let to_buffer buff ofs len v flags =
-  if ofs < 0 || len < 0 || ofs + len > String.length buff
+  if ofs < 0 || len < 0 || ofs + len > Bytes.length buff
   then invalid_arg "Marshal.to_buffer: substring out of bounds"
   else to_buffer_unsafe buff ofs len v flags
 
-let to_buffer' ~buf ~pos ~len v ~mode = to_buffer buf pos len v mode
-
-external from_string_unsafe: string -> int -> 'a
+external from_channel: in_channel -> 'a = "caml_input_value"
+external from_bytes_unsafe: bytes -> int -> 'a
          = "caml_input_value_from_string"
-external data_size_unsafe: string -> int -> int = "caml_marshal_data_size"
+external data_size_unsafe: bytes -> int -> int = "caml_marshal_data_size"
 
 let header_size = 20
 let data_size buff ofs =
-  if ofs < 0 || ofs > String.length buff - header_size
+  if ofs < 0 || ofs > Bytes.length buff - header_size
   then invalid_arg "Marshal.data_size"
   else data_size_unsafe buff ofs
 let total_size buff ofs = header_size + data_size buff ofs
 
-let from_string buff ofs =
-  if ofs < 0 || ofs > String.length buff - header_size
-  then invalid_arg "Marshal.from_size"
+let from_bytes buff ofs =
+  if ofs < 0 || ofs > Bytes.length buff - header_size
+  then invalid_arg "Marshal.from_bytes"
   else begin
     let len = data_size_unsafe buff ofs in
-    if ofs > String.length buff - (header_size + len)
-    then invalid_arg "Marshal.from_string"
-    else from_string_unsafe buff ofs
+    if ofs > Bytes.length buff - (header_size + len)
+    then invalid_arg "Marshal.from_bytes"
+    else from_bytes_unsafe buff ofs
   end
 
-let from_channel = Pervasives.input_value
+let from_string buff ofs = from_bytes (Bytes.unsafe_of_string buff) ofs
diff --git a/otherlibs/threads/pervasives.ml b/otherlibs/threads/pervasives.ml
index e89f78edff..5e55240948 100644
--- a/otherlibs/threads/pervasives.ml
+++ b/otherlibs/threads/pervasives.ml
@@ -168,19 +168,24 @@ type fpclass =
   | FP_nan
 external classify_float : float -> fpclass = "caml_classify_float"
 
-(* String operations -- more in module String *)
+(* String and byte sequence operations -- more in modules String and Bytes *)
 
 external string_length : string -> int = "%string_length"
-external string_create : int -> string = "caml_create_string"
-external string_blit : string -> int -> string -> int -> int -> unit
+external bytes_length : bytes -> int = "%string_length"
+external bytes_create : int -> bytes = "caml_create_string"
+external string_blit : string -> int -> bytes -> int -> int -> unit
                      = "caml_blit_string" "noalloc"
+external bytes_blit : bytes -> int -> bytes -> int -> int -> unit
+                        = "caml_blit_string" "noalloc"
+external bytes_unsafe_to_string : bytes -> string = "%identity"
+external bytes_unsafe_of_string : string -> bytes = "%identity"
 
 let ( ^ ) s1 s2 =
   let l1 = string_length s1 and l2 = string_length s2 in
-  let s = string_create (l1 + l2) in
+  let s = bytes_create (l1 + l2) in
   string_blit s1 0 s 0 l1;
   string_blit s2 0 s l1 l2;
-  s
+  bytes_unsafe_to_string s
 
 (* Character operations -- more in module Char *)
 
@@ -223,12 +228,13 @@ let string_of_int n =
   format_int "%d" n
 
 external int_of_string : string -> int = "caml_int_of_string"
+external string_get : string -> int -> char = "%string_safe_get"
 
 let valid_float_lexem s =
   let l = string_length s in
   let rec loop i =
     if i >= l then s ^ "." else
-    match s.[i] with
+    match string_get s i with
     | '0' .. '9' | '-' -> loop (i + 1)
     | _ -> s
   in
@@ -319,7 +325,7 @@ let flush_all () =
         iter l
   in iter (out_channels_list ())
 
-external unsafe_output_partial : out_channel -> string -> int -> int -> int
+external unsafe_output_partial : out_channel -> bytes -> int -> int -> int
                         = "caml_ml_output_partial"
 
 let rec unsafe_output oc buf pos len =
@@ -343,15 +349,19 @@ let rec output_char oc c =
   with Sys_blocked_io ->
     wait_outchan oc 1; output_char oc c
 
+let output_bytes oc s =
+  unsafe_output oc s 0 (bytes_length s)
+
 let output_string oc s =
-  unsafe_output oc s 0 (string_length s)
+  unsafe_output oc (bytes_unsafe_of_string s) 0 (string_length s)
 
 let output oc s ofs len =
-  if ofs < 0 || len < 0 || ofs > string_length s - len
+  if ofs < 0 || len < 0 || ofs > bytes_length s - len
   then invalid_arg "output"
   else unsafe_output oc s ofs len
 
-let output' oc ~buf ~pos ~len = output oc buf pos len
+let output_substring oc s ofs len =
+  output oc (bytes_unsafe_of_string s) ofs len
 
 let rec output_byte oc b =
   try
@@ -405,7 +415,7 @@ let rec input_char ic =
   with Sys_blocked_io ->
     wait_inchan ic; input_char ic
 
-external unsafe_input_blocking : in_channel -> string -> int -> int -> int
+external unsafe_input_blocking : in_channel -> bytes -> int -> int -> int
                                = "caml_ml_input"
 
 let rec unsafe_input ic s ofs len =
@@ -415,7 +425,7 @@ let rec unsafe_input ic s ofs len =
     wait_inchan ic; unsafe_input ic s ofs len
 
 let input ic s ofs len =
-  if ofs < 0 || len < 0 || ofs > string_length s - len
+  if ofs < 0 || len < 0 || ofs > bytes_length s - len
   then invalid_arg "input"
   else unsafe_input ic s ofs len
 
@@ -428,31 +438,38 @@ let rec unsafe_really_input ic s ofs len =
   end
 
 let really_input ic s ofs len =
-  if ofs < 0 || len < 0 || ofs > string_length s - len
+  if ofs < 0 || len < 0 || ofs > bytes_length s - len
   then invalid_arg "really_input"
   else unsafe_really_input ic s ofs len
 
+let really_input_string ic len =
+  let s = bytes_create len in
+  really_input ic s 0 len;
+  bytes_unsafe_to_string s
+
+external bytes_set : bytes -> int -> char -> unit = "%string_safe_set"
+
 let input_line ic =
-  let buf = ref (string_create 128) in
+  let buf = ref (bytes_create 128) in
   let pos = ref 0 in
   begin try
     while true do
-      if !pos = string_length !buf then begin
-        let newbuf = string_create (2 * !pos) in
-        string_blit !buf 0 newbuf 0 !pos;
+      if !pos = bytes_length !buf then begin
+        let newbuf = bytes_create (2 * !pos) in
+        bytes_blit !buf 0 newbuf 0 !pos;
         buf := newbuf
       end;
       let c = input_char ic in
       if c = '\n' then raise Exit;
-      !buf.[!pos] <- c;
+      bytes_set !buf !pos c;
       incr pos
     done
   with Exit -> ()
      | End_of_file -> if !pos = 0 then raise End_of_file
   end;
-  let res = string_create !pos in
-  string_blit !buf 0 res 0 !pos;
-  res
+  let res = bytes_create !pos in
+  bytes_blit !buf 0 res 0 !pos;
+  bytes_unsafe_to_string res
 
 let rec input_byte ic =
   try
@@ -468,15 +485,15 @@ let input_binary_int ic =
   let b4 = input_byte ic in
   (n1 lsl 24) + (b2 lsl 16) + (b3 lsl 8) + b4
 
-external unmarshal : string -> int -> 'a = "caml_input_value_from_string"
-external marshal_data_size : string -> int -> int = "caml_marshal_data_size"
+external unmarshal : bytes -> int -> 'a = "caml_input_value_from_string"
+external marshal_data_size : bytes -> int -> int = "caml_marshal_data_size"
 
 let input_value ic =
-  let header = string_create 20 in
+  let header = bytes_create 20 in
   really_input ic header 0 20;
   let bsize = marshal_data_size header 0 in
-  let buffer = string_create (20 + bsize) in
-  string_blit header 0 buffer 0 20;
+  let buffer = bytes_create (20 + bsize) in
+  bytes_blit header 0 buffer 0 20;
   really_input ic buffer 20 bsize;
   unmarshal buffer 0
 
@@ -492,6 +509,7 @@ external set_binary_mode_in : in_channel -> bool -> unit
 
 let print_char c = output_char stdout c
 let print_string s = output_string stdout s
+let print_bytes s = output_bytes stdout s
 let print_int i = output_string stdout (string_of_int i)
 let print_float f = output_string stdout (string_of_float f)
 let print_endline s =
@@ -549,12 +567,9 @@ let (( ^^ ) :
     string_to_format (format_to_string fmt1 ^ "%," ^ format_to_string fmt2)
 ;;
 
-let string_of_format fmt =
-  let s = format_to_string fmt in
-  let l = string_length s in
-  let r = string_create l in
-  string_blit s 0 r 0 l;
-  r
+(* Have to return a copy for compatibility with unsafe-string mode *)
+(* String.copy is not available here, so use ^ to make a copy of the string *)
+let string_of_format fmt = format_to_string fmt ^ ""
 
 (* Miscellaneous *)
 
diff --git a/otherlibs/threads/threadUnix.ml b/otherlibs/threads/threadUnix.ml
index fe5ef4fdfc..c086c1f55f 100644
--- a/otherlibs/threads/threadUnix.ml
+++ b/otherlibs/threads/threadUnix.ml
@@ -22,6 +22,8 @@ let system = Unix.system
 let read = Unix.read
 let write = Unix.write
 let single_write = Unix.single_write
+let write_substring = Unix.write_substring
+let single_write_substring = Unix.single_write_substring
 let select = Unix.select
 let pipe = Unix.pipe
 let open_process_in = Unix.open_process_in
@@ -36,7 +38,9 @@ let connect = Unix.connect
 let recv = Unix.recv
 let recvfrom = Unix.recvfrom
 let send = Unix.send
+let send_substring = Unix.send_substring
 let sendto = Unix.sendto
+let sendto_substring = Unix.sendto_substring
 let open_connection = Unix.open_connection
 let establish_server = Unix.establish_server
 
@@ -57,3 +61,6 @@ let rec timed_write fd buff ofs len timeout =
                     timed_write fd buff ofs len timeout
        end
   else raise (Unix_error(ETIMEDOUT, "timed_write", ""))
+
+let timed_write_substring fd buff ofs len timeout =
+  timed_write fd (Bytes.unsafe_of_string buff) ofs len timeout
diff --git a/otherlibs/threads/threadUnix.mli b/otherlibs/threads/threadUnix.mli
index 4ebe28f4f2..52862f98a1 100644
--- a/otherlibs/threads/threadUnix.mli
+++ b/otherlibs/threads/threadUnix.mli
@@ -30,21 +30,27 @@ val system : string -> Unix.process_status
 
 (** {6 Basic input/output} *)
 
-val read : Unix.file_descr -> string -> int -> int -> int
-val write : Unix.file_descr -> string -> int -> int -> int
-val single_write : Unix.file_descr -> string -> int -> int -> int
+val read : Unix.file_descr -> bytes -> int -> int -> int
+val write : Unix.file_descr -> bytes -> int -> int -> int
+val single_write : Unix.file_descr -> bytes -> int -> int -> int
+val write_substring : Unix.file_descr -> string -> int -> int -> int
+val single_write_substring : Unix.file_descr -> string -> int -> int -> int
 
 (** {6 Input/output with timeout} *)
 
-val timed_read : Unix.file_descr -> string -> int -> int -> float -> int
+val timed_read : Unix.file_descr -> bytes -> int -> int -> float -> int
 (** See {!ThreadUnix.timed_write}. *)
 
-val timed_write : Unix.file_descr -> string -> int -> int -> float -> int
+val timed_write : Unix.file_descr -> bytes -> int -> int -> float -> int
 (** Behave as {!ThreadUnix.read} and {!ThreadUnix.write}, except that
    [Unix_error(ETIMEDOUT,_,_)] is raised if no data is
    available for reading or ready for writing after [d] seconds.
    The delay [d] is given in the fifth argument, in seconds. *)
 
+val timed_write_substring :
+      Unix.file_descr -> string -> int -> int -> float -> int
+(** See {!ThreadUnix.timed_write}. *)
+
 (** {6 Polling} *)
 
 val select :
@@ -74,13 +80,18 @@ val socketpair :
 val accept : Unix.file_descr -> Unix.file_descr * Unix.sockaddr
 val connect : Unix.file_descr -> Unix.sockaddr -> unit
 val recv :
-  Unix.file_descr -> string -> int -> int -> Unix.msg_flag list -> int
+  Unix.file_descr -> bytes -> int -> int -> Unix.msg_flag list -> int
 val recvfrom :
-  Unix.file_descr -> string -> int -> int -> Unix.msg_flag list ->
+  Unix.file_descr -> bytes -> int -> int -> Unix.msg_flag list ->
     int * Unix.sockaddr
 val send :
+  Unix.file_descr -> bytes -> int -> int -> Unix.msg_flag list -> int
+val send_substring :
   Unix.file_descr -> string -> int -> int -> Unix.msg_flag list -> int
 val sendto :
+  Unix.file_descr -> bytes -> int -> int -> Unix.msg_flag list ->
+    Unix.sockaddr -> int
+val sendto_substring :
   Unix.file_descr -> string -> int -> int -> Unix.msg_flag list ->
     Unix.sockaddr -> int
 val open_connection : Unix.sockaddr -> in_channel * out_channel
diff --git a/otherlibs/threads/unix.ml b/otherlibs/threads/unix.ml
index 80ea7aed64..a397ec404f 100644
--- a/otherlibs/threads/unix.ml
+++ b/otherlibs/threads/unix.ml
@@ -205,15 +205,15 @@ external openfile : string -> open_flag list -> file_perm -> file_descr
            = "unix_open"
 
 external close : file_descr -> unit = "unix_close"
-external unsafe_read : file_descr -> string -> int -> int -> int = "unix_read"
-external unsafe_write : file_descr -> string -> int -> int -> int
+external unsafe_read : file_descr -> bytes -> int -> int -> int = "unix_read"
+external unsafe_write : file_descr -> bytes -> int -> int -> int
     = "unix_write"
-external unsafe_single_write : file_descr -> string -> int -> int -> int
+external unsafe_single_write : file_descr -> bytes -> int -> int -> int
     = "unix_single_write"
 
 let rec read fd buf ofs len =
   try
-    if ofs < 0 || len < 0 || ofs > String.length buf - len
+    if ofs < 0 || len < 0 || ofs > Bytes.length buf - len
     then invalid_arg "Unix.read"
     else unsafe_read fd buf ofs len
   with Unix_error((EAGAIN | EWOULDBLOCK), _, _) ->
@@ -221,7 +221,7 @@ let rec read fd buf ofs len =
 
 let rec write fd buf ofs len =
   try
-    if ofs < 0 || len < 0 || ofs > String.length buf - len
+    if ofs < 0 || len < 0 || ofs > Bytes.length buf - len
     then invalid_arg "Unix.write"
     else unsafe_write fd buf ofs len
   with Unix_error((EAGAIN | EWOULDBLOCK), _, _) ->
@@ -229,12 +229,18 @@ let rec write fd buf ofs len =
 
 let rec single_write fd buf ofs len =
   try
-    if ofs < 0 || len < 0 || ofs > String.length buf - len
-    then invalid_arg "Unix.partial_write"
+    if ofs < 0 || len < 0 || ofs > Bytes.length buf - len
+    then invalid_arg "Unix.single_write"
     else unsafe_single_write fd buf ofs len
   with Unix_error((EAGAIN | EWOULDBLOCK), _, _) ->
     wait_write fd; single_write fd buf ofs len
 
+let write_substring fd buf ofs len =
+  write fd (Bytes.unsafe_of_string buf) ofs len
+
+let single_write_substring fd buf ofs len =
+  single_write fd (Bytes.unsafe_of_string buf) ofs len
+
 external in_channel_of_descr : file_descr -> in_channel
                              = "caml_ml_open_descriptor_in"
 external out_channel_of_descr : file_descr -> out_channel
@@ -591,21 +597,21 @@ let connect s addr =
     ignore(getpeername s)
 
 external unsafe_recv :
-  file_descr -> string -> int -> int -> msg_flag list -> int
+  file_descr -> bytes -> int -> int -> msg_flag list -> int
                                   = "unix_recv"
 external unsafe_recvfrom :
-  file_descr -> string -> int -> int -> msg_flag list -> int * sockaddr
+  file_descr -> bytes -> int -> int -> msg_flag list -> int * sockaddr
                                   = "unix_recvfrom"
 external unsafe_send :
-  file_descr -> string -> int -> int -> msg_flag list -> int
+  file_descr -> bytes -> int -> int -> msg_flag list -> int
                                   = "unix_send"
 external unsafe_sendto :
-  file_descr -> string -> int -> int -> msg_flag list -> sockaddr -> int
+  file_descr -> bytes -> int -> int -> msg_flag list -> sockaddr -> int
                                   = "unix_sendto" "unix_sendto_native"
 
 let rec recv fd buf ofs len flags =
   try
-    if ofs < 0 || len < 0 || ofs > String.length buf - len
+    if ofs < 0 || len < 0 || ofs > Bytes.length buf - len
     then invalid_arg "Unix.recv"
     else unsafe_recv fd buf ofs len flags
   with Unix_error((EAGAIN | EWOULDBLOCK), _, _) ->
@@ -613,7 +619,7 @@ let rec recv fd buf ofs len flags =
 
 let rec recvfrom fd buf ofs len flags =
   try
-    if ofs < 0 || len < 0 || ofs > String.length buf - len
+    if ofs < 0 || len < 0 || ofs > Bytes.length buf - len
     then invalid_arg "Unix.recvfrom"
     else unsafe_recvfrom fd buf ofs len flags
   with Unix_error((EAGAIN | EWOULDBLOCK), _, _) ->
@@ -622,7 +628,7 @@ let rec recvfrom fd buf ofs len flags =
 
 let rec send fd buf ofs len flags =
   try
-    if ofs < 0 || len < 0 || ofs > String.length buf - len
+    if ofs < 0 || len < 0 || ofs > Bytes.length buf - len
     then invalid_arg "Unix.send"
     else unsafe_send fd buf ofs len flags
   with Unix_error((EAGAIN | EWOULDBLOCK), _, _) ->
@@ -631,13 +637,19 @@ let rec send fd buf ofs len flags =
 
 let rec sendto fd buf ofs len flags addr =
   try
-    if ofs < 0 || len < 0 || ofs > String.length buf - len
+    if ofs < 0 || len < 0 || ofs > Bytes.length buf - len
     then invalid_arg "Unix.sendto"
     else unsafe_sendto fd buf ofs len flags addr
   with Unix_error((EAGAIN | EWOULDBLOCK), _, _) ->
     wait_write fd;
     sendto fd buf ofs len flags addr
 
+let send_substring fd buf ofs len flags =
+  send fd (Bytes.unsafe_of_string buf) ofs len flags
+
+let sendto_substring fd buf ofs len flags addr =
+  sendto fd (Bytes.unsafe_of_string buf) ofs len flags addr
+
 type socket_bool_option =
     SO_DEBUG
   | SO_BROADCAST
diff --git a/otherlibs/unix/.depend b/otherlibs/unix/.depend
index f3f79821d1..63e1d22935 100644
--- a/otherlibs/unix/.depend
+++ b/otherlibs/unix/.depend
@@ -1,498 +1,502 @@
 accept.o: accept.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
- ../../byterun/mlvalues.h ../../byterun/fail.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h \
- socketaddr.h ../../byterun/misc.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h ../../byterun/fail.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h \
+  socketaddr.h ../../byterun/misc.h
 access.o: access.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
- ../../byterun/mlvalues.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h
 addrofstr.o: addrofstr.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h ../../byterun/fail.h \
- unixsupport.h socketaddr.h ../../byterun/misc.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h ../../byterun/fail.h \
+  unixsupport.h socketaddr.h ../../byterun/misc.h
 alarm.o: alarm.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
 bind.o: bind.c ../../byterun/fail.h ../../byterun/compatibility.h \
- ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/mlvalues.h unixsupport.h socketaddr.h ../../byterun/misc.h
+  ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/mlvalues.h unixsupport.h socketaddr.h \
+  ../../byterun/misc.h
 chdir.o: chdir.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h \
- ../../byterun/signals.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h \
+  ../../byterun/signals.h unixsupport.h
 chmod.o: chmod.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h \
- ../../byterun/signals.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h \
+  ../../byterun/signals.h unixsupport.h
 chown.o: chown.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h \
- ../../byterun/signals.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h \
+  ../../byterun/signals.h unixsupport.h
 chroot.o: chroot.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h \
- ../../byterun/signals.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h \
+  ../../byterun/signals.h unixsupport.h
 close.o: close.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/signals.h \
- ../../byterun/mlvalues.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h \
+  ../../byterun/signals.h ../../byterun/mlvalues.h unixsupport.h
 closedir.o: closedir.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h \
- ../../byterun/signals.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h \
+  ../../byterun/signals.h unixsupport.h
 connect.o: connect.c ../../byterun/fail.h ../../byterun/compatibility.h \
- ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/mlvalues.h ../../byterun/signals.h unixsupport.h \
- socketaddr.h ../../byterun/misc.h
+  ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/mlvalues.h ../../byterun/signals.h unixsupport.h \
+  socketaddr.h ../../byterun/misc.h
 cst2constr.o: cst2constr.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/fail.h ../../byterun/mlvalues.h \
- cst2constr.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/fail.h ../../byterun/mlvalues.h \
+  cst2constr.h
 cstringv.o: cstringv.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h unixsupport.h
 dup.o: dup.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
 dup2.o: dup2.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
 envir.o: envir.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
- ../../byterun/mlvalues.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h
 errmsg.o: errmsg.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
- ../../byterun/mlvalues.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h
 execv.o: execv.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h unixsupport.h
 execve.o: execve.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h unixsupport.h
 execvp.o: execvp.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h unixsupport.h
 exit.o: exit.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
 fchmod.o: fchmod.c ../../byterun/fail.h ../../byterun/compatibility.h \
- ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/mlvalues.h ../../byterun/signals.h unixsupport.h
+  ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/mlvalues.h ../../byterun/signals.h unixsupport.h
 fchown.o: fchown.c ../../byterun/fail.h ../../byterun/compatibility.h \
- ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/mlvalues.h ../../byterun/signals.h unixsupport.h
+  ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/mlvalues.h ../../byterun/signals.h unixsupport.h
 fcntl.o: fcntl.c ../../byterun/fail.h ../../byterun/compatibility.h \
- ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/mlvalues.h unixsupport.h
+  ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/mlvalues.h unixsupport.h
 fork.o: fork.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h \
- ../../byterun/debugger.h ../../byterun/mlvalues.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h \
+  ../../byterun/debugger.h ../../byterun/mlvalues.h unixsupport.h
 ftruncate.o: ftruncate.c ../../byterun/fail.h \
- ../../byterun/compatibility.h ../../byterun/misc.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/mlvalues.h ../../byterun/io.h ../../byterun/signals.h \
- unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/misc.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/mlvalues.h ../../byterun/io.h ../../byterun/signals.h \
+  unixsupport.h
 getaddrinfo.o: getaddrinfo.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/fail.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h \
- cst2constr.h socketaddr.h ../../byterun/misc.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
+  ../../byterun/fail.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h \
+  cst2constr.h socketaddr.h ../../byterun/misc.h
 getcwd.o: getcwd.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
- ../../byterun/mlvalues.h ../../byterun/fail.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h ../../byterun/fail.h unixsupport.h
 getegid.o: getegid.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h unixsupport.h
 geteuid.o: geteuid.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h unixsupport.h
 getgid.o: getgid.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
 getgr.o: getgr.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/fail.h \
- ../../byterun/mlvalues.h ../../byterun/alloc.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/fail.h \
+  ../../byterun/mlvalues.h ../../byterun/alloc.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h unixsupport.h
 getgroups.o: getgroups.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/fail.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
+  ../../byterun/fail.h unixsupport.h
 gethost.o: gethost.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/fail.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h \
- socketaddr.h ../../byterun/misc.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
+  ../../byterun/fail.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h \
+  socketaddr.h ../../byterun/misc.h
 gethostname.o: gethostname.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/fail.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
+  ../../byterun/fail.h unixsupport.h
 getlogin.o: getlogin.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
+  unixsupport.h
 getnameinfo.o: getnameinfo.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/fail.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h \
- socketaddr.h ../../byterun/misc.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
+  ../../byterun/fail.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h \
+  socketaddr.h ../../byterun/misc.h
 getpeername.o: getpeername.c ../../byterun/fail.h \
- ../../byterun/compatibility.h ../../byterun/misc.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/mlvalues.h unixsupport.h socketaddr.h ../../byterun/misc.h
+  ../../byterun/compatibility.h ../../byterun/misc.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/mlvalues.h unixsupport.h socketaddr.h \
+  ../../byterun/misc.h
 getpid.o: getpid.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
 getppid.o: getppid.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h unixsupport.h
 getproto.o: getproto.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/fail.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
+  ../../byterun/fail.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h unixsupport.h
 getpw.o: getpw.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
- ../../byterun/mlvalues.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h ../../byterun/fail.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h ../../byterun/fail.h unixsupport.h
 getserv.o: getserv.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/fail.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
+  ../../byterun/fail.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h unixsupport.h
 getsockname.o: getsockname.c ../../byterun/fail.h \
- ../../byterun/compatibility.h ../../byterun/misc.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/mlvalues.h unixsupport.h socketaddr.h ../../byterun/misc.h
+  ../../byterun/compatibility.h ../../byterun/misc.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/mlvalues.h unixsupport.h socketaddr.h \
+  ../../byterun/misc.h
 gettimeofday.o: gettimeofday.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/fail.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
+  ../../byterun/fail.h unixsupport.h
 getuid.o: getuid.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
 gmtime.o: gmtime.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
- ../../byterun/mlvalues.h ../../byterun/fail.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h ../../byterun/fail.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h unixsupport.h
 initgroups.o: initgroups.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/fail.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
+  ../../byterun/fail.h unixsupport.h
 isatty.o: isatty.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
 itimer.o: itimer.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
- ../../byterun/mlvalues.h ../../byterun/fail.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h ../../byterun/fail.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h unixsupport.h
 kill.o: kill.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/fail.h \
- ../../byterun/mlvalues.h unixsupport.h ../../byterun/signals.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/fail.h \
+  ../../byterun/mlvalues.h unixsupport.h ../../byterun/signals.h
 link.o: link.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h \
- ../../byterun/signals.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h \
+  ../../byterun/signals.h unixsupport.h
 listen.o: listen.c ../../byterun/fail.h ../../byterun/compatibility.h \
- ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/mlvalues.h unixsupport.h
+  ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/mlvalues.h unixsupport.h
 lockf.o: lockf.c ../../byterun/fail.h ../../byterun/compatibility.h \
- ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/mlvalues.h ../../byterun/signals.h unixsupport.h
+  ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/mlvalues.h ../../byterun/signals.h unixsupport.h
 lseek.o: lseek.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
- ../../byterun/mlvalues.h ../../byterun/io.h ../../byterun/signals.h \
- unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h ../../byterun/io.h ../../byterun/signals.h \
+  unixsupport.h
 mkdir.o: mkdir.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h \
- ../../byterun/signals.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h \
+  ../../byterun/signals.h unixsupport.h
 mkfifo.o: mkfifo.c ../../byterun/fail.h ../../byterun/compatibility.h \
- ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/mlvalues.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h
+  ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/mlvalues.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h
 nice.o: nice.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
 open.o: open.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
- ../../byterun/mlvalues.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h
 opendir.o: opendir.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h ../../byterun/alloc.h \
- ../../byterun/signals.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h ../../byterun/alloc.h \
+  ../../byterun/signals.h unixsupport.h
 pipe.o: pipe.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
- ../../byterun/mlvalues.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h unixsupport.h
 putenv.o: putenv.c ../../byterun/fail.h ../../byterun/compatibility.h \
- ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/memory.h ../../byterun/gc.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h \
- ../../byterun/mlvalues.h unixsupport.h
+  ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/memory.h ../../byterun/gc.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h \
+  ../../byterun/mlvalues.h unixsupport.h
 read.o: read.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h \
- ../../byterun/signals.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h \
+  ../../byterun/signals.h unixsupport.h
 readdir.o: readdir.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/fail.h ../../byterun/mlvalues.h \
- ../../byterun/alloc.h ../../byterun/signals.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/fail.h ../../byterun/mlvalues.h \
+  ../../byterun/alloc.h ../../byterun/signals.h unixsupport.h
 readlink.o: readlink.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h ../../byterun/alloc.h \
- ../../byterun/fail.h ../../byterun/signals.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h ../../byterun/alloc.h \
+  ../../byterun/fail.h ../../byterun/signals.h unixsupport.h
 rename.o: rename.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h \
- ../../byterun/signals.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h \
+  ../../byterun/signals.h unixsupport.h
 rewinddir.o: rewinddir.c ../../byterun/fail.h \
- ../../byterun/compatibility.h ../../byterun/misc.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/mlvalues.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/misc.h \
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/mlvalues.h unixsupport.h
 rmdir.o: rmdir.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h \
- ../../byterun/signals.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h \
+  ../../byterun/signals.h unixsupport.h
 select.o: select.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
- ../../byterun/mlvalues.h ../../byterun/fail.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h ../../byterun/fail.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h
 sendrecv.o: sendrecv.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/fail.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h \
- socketaddr.h ../../byterun/misc.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
+  ../../byterun/fail.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h \
+  socketaddr.h ../../byterun/misc.h
 setgid.o: setgid.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
 setgroups.o: setgroups.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/fail.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
+  ../../byterun/fail.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h unixsupport.h
 setsid.o: setsid.c ../../byterun/fail.h ../../byterun/compatibility.h \
- ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/mlvalues.h unixsupport.h
+  ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/mlvalues.h unixsupport.h
 setuid.o: setuid.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
 shutdown.o: shutdown.c ../../byterun/fail.h ../../byterun/compatibility.h \
- ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/mlvalues.h unixsupport.h
+  ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/mlvalues.h unixsupport.h
 signals.o: signals.c ../../byterun/alloc.h ../../byterun/compatibility.h \
- ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/fail.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h ../../byterun/mlvalues.h \
- ../../byterun/signals.h unixsupport.h
+  ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/fail.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h ../../byterun/mlvalues.h \
+  ../../byterun/signals.h unixsupport.h
 sleep.o: sleep.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/signals.h \
- ../../byterun/mlvalues.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h \
+  ../../byterun/signals.h ../../byterun/mlvalues.h unixsupport.h
 socket.o: socket.c ../../byterun/fail.h ../../byterun/compatibility.h \
- ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/mlvalues.h unixsupport.h
+  ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/mlvalues.h unixsupport.h
 socketaddr.o: socketaddr.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/memory.h ../../byterun/gc.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h unixsupport.h \
- socketaddr.h ../../byterun/misc.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
+  ../../byterun/memory.h ../../byterun/gc.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h unixsupport.h \
+  socketaddr.h ../../byterun/misc.h
 socketpair.o: socketpair.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/fail.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
+  ../../byterun/fail.h unixsupport.h
 sockopt.o: sockopt.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h ../../byterun/alloc.h \
- ../../byterun/fail.h unixsupport.h socketaddr.h ../../byterun/misc.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h ../../byterun/alloc.h \
+  ../../byterun/fail.h unixsupport.h socketaddr.h ../../byterun/misc.h
 stat.o: stat.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h ../../byterun/alloc.h \
- ../../byterun/signals.h unixsupport.h cst2constr.h ../../byterun/io.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h ../../byterun/alloc.h \
+  ../../byterun/signals.h unixsupport.h cst2constr.h ../../byterun/io.h
 strofaddr.o: strofaddr.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/fail.h unixsupport.h socketaddr.h ../../byterun/misc.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
+  ../../byterun/fail.h unixsupport.h socketaddr.h ../../byterun/misc.h
 symlink.o: symlink.c ../../byterun/fail.h ../../byterun/compatibility.h \
- ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/mlvalues.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h
+  ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/mlvalues.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h
 termios.o: termios.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/fail.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
+  ../../byterun/fail.h unixsupport.h
 time.o: time.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
- ../../byterun/mlvalues.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h unixsupport.h
 times.o: times.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
- ../../byterun/mlvalues.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h unixsupport.h
 truncate.o: truncate.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h ../../byterun/fail.h \
- ../../byterun/signals.h ../../byterun/io.h unixsupport.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h ../../byterun/fail.h \
+  ../../byterun/signals.h ../../byterun/io.h unixsupport.h
 umask.o: umask.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h unixsupport.h
 unixsupport.o: unixsupport.c ../../byterun/mlvalues.h \
- ../../byterun/compatibility.h ../../byterun/config.h \
- ../../byterun/../config/m.h ../../byterun/../config/s.h \
- ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
- ../../byterun/callback.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h ../../byterun/fail.h unixsupport.h cst2constr.h
+  ../../byterun/compatibility.h ../../byterun/config.h \
+  ../../byterun/../config/m.h ../../byterun/../config/s.h \
+  ../../byterun/misc.h ../../byterun/alloc.h ../../byterun/mlvalues.h \
+  ../../byterun/callback.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h ../../byterun/fail.h unixsupport.h \
+  cst2constr.h
 unlink.o: unlink.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h \
- ../../byterun/signals.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h \
+  ../../byterun/signals.h unixsupport.h
 utimes.o: utimes.c ../../byterun/fail.h ../../byterun/compatibility.h \
- ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/mlvalues.h \
- ../../byterun/mlvalues.h ../../byterun/memory.h ../../byterun/gc.h \
- ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h
+  ../../byterun/misc.h ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/mlvalues.h \
+  ../../byterun/mlvalues.h ../../byterun/memory.h ../../byterun/gc.h \
+  ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h
 wait.o: wait.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
- ../../byterun/mlvalues.h ../../byterun/fail.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/major_gc.h ../../byterun/freelist.h \
- ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/alloc.h \
+  ../../byterun/mlvalues.h ../../byterun/fail.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/major_gc.h ../../byterun/freelist.h \
+  ../../byterun/minor_gc.h ../../byterun/signals.h unixsupport.h
 write.o: write.c ../../byterun/mlvalues.h ../../byterun/compatibility.h \
- ../../byterun/config.h ../../byterun/../config/m.h \
- ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
- ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
- ../../byterun/freelist.h ../../byterun/minor_gc.h \
- ../../byterun/signals.h unixsupport.h
+  ../../byterun/config.h ../../byterun/../config/m.h \
+  ../../byterun/../config/s.h ../../byterun/misc.h ../../byterun/memory.h \
+  ../../byterun/gc.h ../../byterun/mlvalues.h ../../byterun/major_gc.h \
+  ../../byterun/freelist.h ../../byterun/minor_gc.h \
+  ../../byterun/signals.h unixsupport.h
 unix.cmi :
 unixLabels.cmi : unix.cmi
 unix.cmo : unix.cmi
diff --git a/otherlibs/unix/unix.ml b/otherlibs/unix/unix.ml
index 8bd935f4cb..d18b338adb 100644
--- a/otherlibs/unix/unix.ml
+++ b/otherlibs/unix/unix.ml
@@ -237,27 +237,34 @@ external openfile : string -> open_flag list -> file_perm -> file_descr
            = "unix_open"
 
 external close : file_descr -> unit = "unix_close"
-external unsafe_read : file_descr -> string -> int -> int -> int = "unix_read"
-external unsafe_write : file_descr -> string -> int -> int -> int = "unix_write"
-external unsafe_single_write : file_descr -> string -> int -> int -> int
+external unsafe_read : file_descr -> bytes -> int -> int -> int
+   = "unix_read"
+external unsafe_write : file_descr -> bytes -> int -> int -> int = "unix_write"
+external unsafe_single_write : file_descr -> bytes -> int -> int -> int
    = "unix_single_write"
 
 let read fd buf ofs len =
-  if ofs < 0 || len < 0 || ofs > String.length buf - len
+  if ofs < 0 || len < 0 || ofs > Bytes.length buf - len
   then invalid_arg "Unix.read"
   else unsafe_read fd buf ofs len
 let write fd buf ofs len =
-  if ofs < 0 || len < 0 || ofs > String.length buf - len
+  if ofs < 0 || len < 0 || ofs > Bytes.length buf - len
   then invalid_arg "Unix.write"
   else unsafe_write fd buf ofs len
 (* write misbehaves because it attempts to write all data by making repeated
    calls to the Unix write function (see comment in write.c and unix.mli).
-   partial_write fixes this by never calling write twice. *)
+   single_write fixes this by never calling write twice. *)
 let single_write fd buf ofs len =
-  if ofs < 0 || len < 0 || ofs > String.length buf - len
+  if ofs < 0 || len < 0 || ofs > Bytes.length buf - len
   then invalid_arg "Unix.single_write"
   else unsafe_single_write fd buf ofs len
 
+let write_substring fd buf ofs len =
+  write fd (Bytes.unsafe_of_string buf) ofs len
+
+let single_write_substring fd buf ofs len =
+  single_write fd (Bytes.unsafe_of_string buf) ofs len
+
 external in_channel_of_descr : file_descr -> in_channel
                              = "caml_ml_open_descriptor_in"
 external out_channel_of_descr : file_descr -> out_channel
@@ -529,35 +536,41 @@ external getsockname : file_descr -> sockaddr = "unix_getsockname"
 external getpeername : file_descr -> sockaddr = "unix_getpeername"
 
 external unsafe_recv :
-  file_descr -> string -> int -> int -> msg_flag list -> int
+  file_descr -> bytes -> int -> int -> msg_flag list -> int
                                   = "unix_recv"
 external unsafe_recvfrom :
-  file_descr -> string -> int -> int -> msg_flag list -> int * sockaddr
+  file_descr -> bytes -> int -> int -> msg_flag list -> int * sockaddr
                                   = "unix_recvfrom"
 external unsafe_send :
-  file_descr -> string -> int -> int -> msg_flag list -> int
+  file_descr -> bytes -> int -> int -> msg_flag list -> int
                                   = "unix_send"
 external unsafe_sendto :
-  file_descr -> string -> int -> int -> msg_flag list -> sockaddr -> int
+  file_descr -> bytes -> int -> int -> msg_flag list -> sockaddr -> int
                                   = "unix_sendto" "unix_sendto_native"
 
 let recv fd buf ofs len flags =
-  if ofs < 0 || len < 0 || ofs > String.length buf - len
+  if ofs < 0 || len < 0 || ofs > Bytes.length buf - len
   then invalid_arg "Unix.recv"
   else unsafe_recv fd buf ofs len flags
 let recvfrom fd buf ofs len flags =
-  if ofs < 0 || len < 0 || ofs > String.length buf - len
+  if ofs < 0 || len < 0 || ofs > Bytes.length buf - len
   then invalid_arg "Unix.recvfrom"
   else unsafe_recvfrom fd buf ofs len flags
 let send fd buf ofs len flags =
-  if ofs < 0 || len < 0 || ofs > String.length buf - len
+  if ofs < 0 || len < 0 || ofs > Bytes.length buf - len
   then invalid_arg "Unix.send"
   else unsafe_send fd buf ofs len flags
 let sendto fd buf ofs len flags addr =
-  if ofs < 0 || len < 0 || ofs > String.length buf - len
+  if ofs < 0 || len < 0 || ofs > Bytes.length buf - len
   then invalid_arg "Unix.sendto"
   else unsafe_sendto fd buf ofs len flags addr
 
+let send_substring fd buf ofs len flags =
+  send fd (Bytes.unsafe_of_string buf) ofs len flags
+
+let sendto_substring fd buf ofs len flags addr =
+  sendto fd (Bytes.unsafe_of_string buf) ofs len flags addr
+
 type socket_bool_option =
     SO_DEBUG
   | SO_BROADCAST
diff --git a/otherlibs/unix/unix.mli b/otherlibs/unix/unix.mli
index efc3fe6fc4..59e5199357 100644
--- a/otherlibs/unix/unix.mli
+++ b/otherlibs/unix/unix.mli
@@ -259,23 +259,31 @@ val openfile : string -> open_flag list -> file_perm -> file_descr
 val close : file_descr -> unit
 (** Close a file descriptor. *)
 
-val read : file_descr -> string -> int -> int -> int
-(** [read fd buff ofs len] reads [len] characters from descriptor
-   [fd], storing them in string [buff], starting at position [ofs]
-   in string [buff]. Return the number of characters actually read. *)
-
-val write : file_descr -> string -> int -> int -> int
-(** [write fd buff ofs len] writes [len] characters to descriptor
-   [fd], taking them from string [buff], starting at position [ofs]
-   in string [buff]. Return the number of characters actually
-   written.  [write] repeats the writing operation until all characters
-   have been written or an error occurs.  *)
-
-val single_write : file_descr -> string -> int -> int -> int
+val read : file_descr -> bytes -> int -> int -> int
+(** [read fd buff ofs len] reads [len] bytes from descriptor [fd],
+    storing them in byte sequence [buff], starting at position [ofs] in
+    [buff]. Return the number of bytes actually read. *)
+
+val write : file_descr -> bytes -> int -> int -> int
+(** [write fd buff ofs len] writes [len] bytes to descriptor [fd],
+    taking them from byte sequence [buff], starting at position [ofs]
+    in [buff]. Return the number of bytes actually written.  [write]
+    repeats the writing operation until all bytes have been written or
+    an error occurs.  *)
+
+val single_write : file_descr -> bytes -> int -> int -> int
 (** Same as [write], but attempts to write only once.
    Thus, if an error occurs, [single_write] guarantees that no data
    has been written. *)
 
+val write_substring : file_descr -> string -> int -> int -> int
+(** Same as [write], but take the data from a string instead of a byte
+    sequence. *)
+
+val single_write_substring : file_descr -> string -> int -> int -> int
+(** Same as [single_write], but take the data from a string instead of
+    a byte sequence. *)
+
 (** {6 Interfacing with the standard input/output library} *)
 
 
@@ -994,20 +1002,28 @@ type msg_flag =
 (** The flags for {!Unix.recv},  {!Unix.recvfrom},
    {!Unix.send} and {!Unix.sendto}. *)
 
-val recv : file_descr -> string -> int -> int -> msg_flag list -> int
+val recv : file_descr -> bytes -> int -> int -> msg_flag list -> int
 (** Receive data from a connected socket. *)
 
 val recvfrom :
-  file_descr -> string -> int -> int -> msg_flag list -> int * sockaddr
+  file_descr -> bytes -> int -> int -> msg_flag list -> int * sockaddr
 (** Receive data from an unconnected socket. *)
 
-val send : file_descr -> string -> int -> int -> msg_flag list -> int
+val send : file_descr -> bytes -> int -> int -> msg_flag list -> int
 (** Send data over a connected socket. *)
 
+val send_substring : file_descr -> string -> int -> int -> msg_flag list -> int
+(** Same as [send], but take the data from a string instead of a byte
+    sequence. *)
+
 val sendto :
-  file_descr -> string -> int -> int -> msg_flag list -> sockaddr -> int
+  file_descr -> bytes -> int -> int -> msg_flag list -> sockaddr -> int
 (** Send data over an unconnected socket. *)
 
+val sendto_substring :
+  file_descr -> string -> int -> int -> msg_flag list -> sockaddr -> int
+(** Same as [sendto], but take the data from a string instead of a
+    byte sequence. *)
 
 
 (** {6 Socket options} *)
diff --git a/otherlibs/unix/unixLabels.mli b/otherlibs/unix/unixLabels.mli
index 53e16b1d76..76ff890b12 100644
--- a/otherlibs/unix/unixLabels.mli
+++ b/otherlibs/unix/unixLabels.mli
@@ -261,23 +261,32 @@ val openfile : string -> mode:open_flag list -> perm:file_perm -> file_descr
 val close : file_descr -> unit
 (** Close a file descriptor. *)
 
-val read : file_descr -> buf:string -> pos:int -> len:int -> int
-(** [read fd buff ofs len] reads [len] characters from descriptor
-   [fd], storing them in string [buff], starting at position [ofs]
-   in string [buff]. Return the number of characters actually read. *)
-
-val write : file_descr -> buf:string -> pos:int -> len:int -> int
-(** [write fd buff ofs len] writes [len] characters to descriptor
-   [fd], taking them from string [buff], starting at position [ofs]
-   in string [buff]. Return the number of characters actually
-   written.  [write] repeats the writing operation until all characters
-   have been written or an error occurs.  *)
-
-val single_write : file_descr -> buf:string -> pos:int -> len:int -> int
+val read : file_descr -> buf:bytes -> pos:int -> len:int -> int
+(** [read fd buff ofs len] reads [len] bytes from descriptor [fd],
+    storing them in byte sequence [buff], starting at position [ofs] in
+    [buff]. Return the number of bytes actually read. *)
+
+val write : file_descr -> buf:bytes -> pos:int -> len:int -> int
+(** [write fd buff ofs len] writes [len] bytes to descriptor [fd],
+    taking them from byte sequence [buff], starting at position [ofs]
+    in [buff]. Return the number of bytes actually written.  [write]
+    repeats the writing operation until all bytes have been written or
+    an error occurs.  *)
+
+val single_write : file_descr -> buf:bytes -> pos:int -> len:int -> int
 (** Same as [write], but attempts to write only once.
    Thus, if an error occurs, [single_write] guarantees that no data
    has been written. *)
 
+val write_substring : file_descr -> buf:string -> pos:int -> len:int -> int
+(** Same as [write], but take the data from a string instead of a byte
+    sequence. *)
+
+val single_write_substring :
+  file_descr -> buf:string -> pos:int -> len:int -> int
+(** Same as [single_write], but take the data from a string instead of
+    a byte sequence. *)
+
 (** {6 Interfacing with the standard input/output library} *)
 
 
@@ -1000,23 +1009,34 @@ type msg_flag = Unix.msg_flag =
    {!UnixLabels.send} and {!UnixLabels.sendto}. *)
 
 val recv :
-  file_descr -> buf:string -> pos:int -> len:int -> mode:msg_flag list -> int
+  file_descr -> buf:bytes -> pos:int -> len:int -> mode:msg_flag list -> int
 (** Receive data from a connected socket. *)
 
 val recvfrom :
-  file_descr -> buf:string -> pos:int -> len:int -> mode:msg_flag list ->
+  file_descr -> buf:bytes -> pos:int -> len:int -> mode:msg_flag list ->
     int * sockaddr
 (** Receive data from an unconnected socket. *)
 
 val send :
-  file_descr -> buf:string -> pos:int -> len:int -> mode:msg_flag list -> int
+  file_descr -> buf:bytes -> pos:int -> len:int -> mode:msg_flag list -> int
 (** Send data over a connected socket. *)
 
+val send_substring :
+  file_descr -> buf:string -> pos:int -> len:int -> mode:msg_flag list -> int
+(** Same as [send], but take the data from a string instead of a byte
+    sequence. *)
+
 val sendto :
-  file_descr -> buf:string -> pos:int -> len:int -> mode:msg_flag list ->
+  file_descr -> buf:bytes -> pos:int -> len:int -> mode:msg_flag list ->
     addr:sockaddr -> int
 (** Send data over an unconnected socket. *)
 
+val sendto_substring :
+  file_descr -> bug:string -> pos:int -> len:int -> mode:msg_flag list
+  -> sockaddr -> int
+(** Same as [sendto], but take the data from a string instead of a
+    byte sequence. *)
+
 
 
 (** {6 Socket options} *)
diff --git a/parsing/ast_mapper.ml b/parsing/ast_mapper.ml
index eba4d76c6a..4ccd13ae03 100644
--- a/parsing/ast_mapper.ml
+++ b/parsing/ast_mapper.ml
@@ -586,8 +586,9 @@ let default_mapper =
 
 let apply ~source ~target mapper =
   let ic = open_in_bin source in
-  let magic = String.create (String.length Config.ast_impl_magic_number) in
-  really_input ic magic 0 (String.length magic);
+  let magic =
+    really_input_string ic (String.length Config.ast_impl_magic_number)
+  in
   if magic <> Config.ast_impl_magic_number
   && magic <> Config.ast_intf_magic_number then
     failwith "Ast_mapper: unknown magic number";
diff --git a/parsing/lexer.mll b/parsing/lexer.mll
index 955e5dec25..d096356585 100644
--- a/parsing/lexer.mll
+++ b/parsing/lexer.mll
@@ -94,7 +94,7 @@ let keyword_table =
 
 (* To buffer string literals *)
 
-let initial_string_buffer = String.create 256
+let initial_string_buffer = Bytes.create 256
 let string_buff = ref initial_string_buffer
 let string_index = ref 0
 
@@ -103,12 +103,12 @@ let reset_string_buffer () =
   string_index := 0
 
 let store_string_char c =
-  if !string_index >= String.length (!string_buff) then begin
-    let new_buff = String.create (String.length (!string_buff) * 2) in
-      String.blit (!string_buff) 0 new_buff 0 (String.length (!string_buff));
-      string_buff := new_buff
+  if !string_index >= Bytes.length !string_buff then begin
+    let new_buff = Bytes.create (Bytes.length (!string_buff) * 2) in
+    Bytes.blit !string_buff 0 new_buff 0 (Bytes.length !string_buff);
+    string_buff := new_buff
   end;
-  String.unsafe_set (!string_buff) (!string_index) c;
+  Bytes.unsafe_set !string_buff !string_index c;
   incr string_index
 
 let store_string s =
@@ -120,7 +120,7 @@ let store_lexeme lexbuf =
   store_string (Lexing.lexeme lexbuf)
 
 let get_stored_string () =
-  let s = String.sub (!string_buff) 0 (!string_index) in
+  let s = Bytes.sub_string !string_buff 0 !string_index in
   string_buff := initial_string_buffer;
   s
 
@@ -181,13 +181,14 @@ let cvt_nativeint_literal s =
 
 let remove_underscores s =
   let l = String.length s in
+  let b = Bytes.create l in
   let rec remove src dst =
     if src >= l then
-      if dst >= l then s else String.sub s 0 dst
+      if dst >= l then s else Bytes.sub_string b 0 dst
     else
       match s.[src] with
         '_' -> remove (src + 1) dst
-      |  c  -> s.[dst] <- c; remove (src + 1) (dst + 1)
+      |  c  -> Bytes.set b dst c; remove (src + 1) (dst + 1)
   in remove 0 0
 
 (* recover the name from a LABEL or OPTLABEL token *)
diff --git a/parsing/location.ml b/parsing/location.ml
index 669f2a2433..1662b9c398 100644
--- a/parsing/location.ml
+++ b/parsing/location.ml
@@ -83,7 +83,7 @@ let highlight_terminfo ppf num_lines lb locs =
   (* Count number of lines in phrase *)
   let lines = ref !num_loc_lines in
   for i = pos0 to lb.lex_buffer_len - 1 do
-    if lb.lex_buffer.[i] = '\n' then incr lines
+    if Bytes.get lb.lex_buffer i = '\n' then incr lines
   done;
   (* If too many lines, give up *)
   if !lines >= num_lines - 2 then raise Exit;
@@ -98,7 +98,7 @@ let highlight_terminfo ppf num_lines lb locs =
       Terminfo.standout true;
     if List.exists (fun loc -> pos = loc.loc_end.pos_cnum) locs then
       Terminfo.standout false;
-    let c = lb.lex_buffer.[pos + pos0] in
+    let c = Bytes.get lb.lex_buffer (pos + pos0) in
     print_char c;
     bol := (c = '\n')
   done;
@@ -119,7 +119,7 @@ let highlight_dumb ppf lb loc =
   (* Determine line numbers for the start and end points *)
   let line_start = ref 0 and line_end = ref 0 in
   for pos = 0 to end_pos do
-    if lb.lex_buffer.[pos + pos0] = '\n' then begin
+    if Bytes.get lb.lex_buffer (pos + pos0) = '\n' then begin
       if loc.loc_start.pos_cnum > pos then incr line_start;
       if loc.loc_end.pos_cnum   > pos then incr line_end;
     end
@@ -132,7 +132,7 @@ let highlight_dumb ppf lb loc =
   let line = ref 0 in
   let pos_at_bol = ref 0 in
   for pos = 0 to end_pos do
-    match lb.lex_buffer.[pos + pos0] with
+    match Bytes.get lb.lex_buffer (pos + pos0) with
     | '\n' ->
       if !line = !line_start && !line = !line_end then begin
         (* loc is on one line: underline location *)
diff --git a/stdlib/.depend b/stdlib/.depend
index e5b65ad513..e7492ebf54 100644
--- a/stdlib/.depend
+++ b/stdlib/.depend
@@ -2,6 +2,8 @@ arg.cmi :
 array.cmi :
 arrayLabels.cmi :
 buffer.cmi :
+bytes.cmi :
+bytesLabels.cmi :
 callback.cmi :
 camlinternalLazy.cmi :
 camlinternalMod.cmi : obj.cmi
@@ -36,7 +38,8 @@ scanf.cmi : pervasives.cmi
 set.cmi :
 sort.cmi :
 stack.cmi :
-stdLabels.cmi : stringLabels.cmi listLabels.cmi arrayLabels.cmi
+stdLabels.cmi : stringLabels.cmi listLabels.cmi bytesLabels.cmi \
+    arrayLabels.cmi
 stream.cmi :
 string.cmi :
 stringLabels.cmi :
@@ -50,8 +53,12 @@ array.cmo : array.cmi
 array.cmx : array.cmi
 arrayLabels.cmo : array.cmi arrayLabels.cmi
 arrayLabels.cmx : array.cmx arrayLabels.cmi
-buffer.cmo : sys.cmi string.cmi buffer.cmi
-buffer.cmx : sys.cmx string.cmx buffer.cmi
+buffer.cmo : sys.cmi string.cmi bytes.cmi buffer.cmi
+buffer.cmx : sys.cmx string.cmx bytes.cmx buffer.cmi
+bytes.cmo : pervasives.cmi list.cmi char.cmi bytes.cmi
+bytes.cmx : pervasives.cmx list.cmx char.cmx bytes.cmi
+bytesLabels.cmo : bytes.cmi bytesLabels.cmi
+bytesLabels.cmx : bytes.cmx bytesLabels.cmi
 callback.cmo : obj.cmi callback.cmi
 callback.cmx : obj.cmx callback.cmi
 camlinternalLazy.cmo : obj.cmi camlinternalLazy.cmi
@@ -68,8 +75,8 @@ char.cmo : char.cmi
 char.cmx : char.cmi
 complex.cmo : complex.cmi
 complex.cmx : complex.cmi
-digest.cmo : string.cmi char.cmi digest.cmi
-digest.cmx : string.cmx char.cmx digest.cmi
+digest.cmo : string.cmi char.cmi bytes.cmi digest.cmi
+digest.cmx : string.cmx char.cmx bytes.cmx digest.cmi
 filename.cmo : sys.cmi string.cmi random.cmi printf.cmi lazy.cmi buffer.cmi \
     filename.cmi
 filename.cmx : sys.cmx string.cmx random.cmx printf.cmx lazy.cmx buffer.cmx \
@@ -80,8 +87,10 @@ format.cmx : string.cmx printf.cmx pervasives.cmx obj.cmx list.cmx \
     buffer.cmx format.cmi
 gc.cmo : sys.cmi printf.cmi gc.cmi
 gc.cmx : sys.cmx printf.cmx gc.cmi
-genlex.cmo : string.cmi stream.cmi list.cmi hashtbl.cmi char.cmi genlex.cmi
-genlex.cmx : string.cmx stream.cmx list.cmx hashtbl.cmx char.cmx genlex.cmi
+genlex.cmo : string.cmi stream.cmi list.cmi hashtbl.cmi char.cmi bytes.cmi \
+    genlex.cmi
+genlex.cmx : string.cmx stream.cmx list.cmx hashtbl.cmx char.cmx bytes.cmx \
+    genlex.cmi
 hashtbl.cmo : sys.cmi string.cmi random.cmi obj.cmi lazy.cmi array.cmi \
     hashtbl.cmi
 hashtbl.cmx : sys.cmx string.cmx random.cmx obj.cmx lazy.cmx array.cmx \
@@ -92,16 +101,16 @@ int64.cmo : pervasives.cmi int64.cmi
 int64.cmx : pervasives.cmx int64.cmi
 lazy.cmo : obj.cmi camlinternalLazy.cmi lazy.cmi
 lazy.cmx : obj.cmx camlinternalLazy.cmx lazy.cmi
-lexing.cmo : sys.cmi string.cmi array.cmi lexing.cmi
-lexing.cmx : sys.cmx string.cmx array.cmx lexing.cmi
+lexing.cmo : sys.cmi string.cmi bytes.cmi array.cmi lexing.cmi
+lexing.cmx : sys.cmx string.cmx bytes.cmx array.cmx lexing.cmi
 list.cmo : list.cmi
 list.cmx : list.cmi
 listLabels.cmo : list.cmi listLabels.cmi
 listLabels.cmx : list.cmx listLabels.cmi
 map.cmo : map.cmi
 map.cmx : map.cmi
-marshal.cmo : string.cmi marshal.cmi
-marshal.cmx : string.cmx marshal.cmi
+marshal.cmo : obj.cmi bytes.cmi marshal.cmi
+marshal.cmx : obj.cmx bytes.cmx marshal.cmi
 moreLabels.cmo : set.cmi map.cmi hashtbl.cmi moreLabels.cmi
 moreLabels.cmx : set.cmx map.cmx hashtbl.cmx moreLabels.cmi
 nativeint.cmo : sys.cmi pervasives.cmi nativeint.cmi
@@ -116,10 +125,10 @@ pervasives.cmo : pervasives.cmi
 pervasives.cmx : pervasives.cmi
 printexc.cmo : printf.cmi obj.cmi buffer.cmi array.cmi printexc.cmi
 printexc.cmx : printf.cmx obj.cmx buffer.cmx array.cmx printexc.cmi
-printf.cmo : string.cmi obj.cmi list.cmi char.cmi buffer.cmi array.cmi \
-    printf.cmi
-printf.cmx : string.cmx obj.cmx list.cmx char.cmx buffer.cmx array.cmx \
-    printf.cmi
+printf.cmo : string.cmi obj.cmi list.cmi char.cmi bytes.cmi buffer.cmi \
+    array.cmi printf.cmi
+printf.cmx : string.cmx obj.cmx list.cmx char.cmx bytes.cmx buffer.cmx \
+    array.cmx printf.cmi
 queue.cmo : obj.cmi queue.cmi
 queue.cmx : obj.cmx queue.cmi
 random.cmo : string.cmi pervasives.cmi nativeint.cmi int64.cmi int32.cmi \
@@ -127,9 +136,9 @@ random.cmo : string.cmi pervasives.cmi nativeint.cmi int64.cmi int32.cmi \
 random.cmx : string.cmx pervasives.cmx nativeint.cmx int64.cmx int32.cmx \
     digest.cmx char.cmx array.cmx random.cmi
 scanf.cmo : string.cmi printf.cmi pervasives.cmi obj.cmi list.cmi \
-    hashtbl.cmi buffer.cmi array.cmi scanf.cmi
+    hashtbl.cmi bytes.cmi buffer.cmi array.cmi scanf.cmi
 scanf.cmx : string.cmx printf.cmx pervasives.cmx obj.cmx list.cmx \
-    hashtbl.cmx buffer.cmx array.cmx scanf.cmi
+    hashtbl.cmx bytes.cmx buffer.cmx array.cmx scanf.cmi
 set.cmo : list.cmi set.cmi
 set.cmx : list.cmx set.cmi
 sort.cmo : array.cmi sort.cmi
@@ -142,10 +151,10 @@ stdLabels.cmx : stringLabels.cmx listLabels.cmx arrayLabels.cmx \
     stdLabels.cmi
 std_exit.cmo :
 std_exit.cmx :
-stream.cmo : string.cmi obj.cmi list.cmi lazy.cmi stream.cmi
-stream.cmx : string.cmx obj.cmx list.cmx lazy.cmx stream.cmi
-string.cmo : pervasives.cmi list.cmi char.cmi string.cmi
-string.cmx : pervasives.cmx list.cmx char.cmx string.cmi
+stream.cmo : string.cmi obj.cmi list.cmi lazy.cmi bytes.cmi stream.cmi
+stream.cmx : string.cmx obj.cmx list.cmx lazy.cmx bytes.cmx stream.cmi
+string.cmo : pervasives.cmi obj.cmi bytes.cmi string.cmi
+string.cmx : pervasives.cmx obj.cmx bytes.cmx string.cmi
 stringLabels.cmo : string.cmi stringLabels.cmi
 stringLabels.cmx : string.cmx stringLabels.cmi
 sys.cmo : sys.cmi
@@ -160,8 +169,12 @@ array.cmo : array.cmi
 array.p.cmx : array.cmi
 arrayLabels.cmo : array.cmi arrayLabels.cmi
 arrayLabels.p.cmx : array.p.cmx arrayLabels.cmi
-buffer.cmo : sys.cmi string.cmi buffer.cmi
-buffer.p.cmx : sys.p.cmx string.p.cmx buffer.cmi
+buffer.cmo : sys.cmi string.cmi bytes.cmi buffer.cmi
+buffer.p.cmx : sys.p.cmx string.p.cmx bytes.p.cmx buffer.cmi
+bytes.cmo : pervasives.cmi list.cmi char.cmi bytes.cmi
+bytes.p.cmx : pervasives.p.cmx list.p.cmx char.p.cmx bytes.cmi
+bytesLabels.cmo : bytes.cmi bytesLabels.cmi
+bytesLabels.p.cmx : bytes.p.cmx bytesLabels.cmi
 callback.cmo : obj.cmi callback.cmi
 callback.p.cmx : obj.p.cmx callback.cmi
 camlinternalLazy.cmo : obj.cmi camlinternalLazy.cmi
@@ -178,8 +191,8 @@ char.cmo : char.cmi
 char.p.cmx : char.cmi
 complex.cmo : complex.cmi
 complex.p.cmx : complex.cmi
-digest.cmo : string.cmi char.cmi digest.cmi
-digest.p.cmx : string.p.cmx char.p.cmx digest.cmi
+digest.cmo : string.cmi char.cmi bytes.cmi digest.cmi
+digest.p.cmx : string.p.cmx char.p.cmx bytes.p.cmx digest.cmi
 filename.cmo : sys.cmi string.cmi random.cmi printf.cmi lazy.cmi buffer.cmi \
     filename.cmi
 filename.p.cmx : sys.p.cmx string.p.cmx random.p.cmx printf.p.cmx lazy.p.cmx buffer.p.cmx \
@@ -190,8 +203,10 @@ format.p.cmx : string.p.cmx printf.p.cmx pervasives.p.cmx obj.p.cmx list.p.cmx \
     buffer.p.cmx format.cmi
 gc.cmo : sys.cmi printf.cmi gc.cmi
 gc.p.cmx : sys.p.cmx printf.p.cmx gc.cmi
-genlex.cmo : string.cmi stream.cmi list.cmi hashtbl.cmi char.cmi genlex.cmi
-genlex.p.cmx : string.p.cmx stream.p.cmx list.p.cmx hashtbl.p.cmx char.p.cmx genlex.cmi
+genlex.cmo : string.cmi stream.cmi list.cmi hashtbl.cmi char.cmi bytes.cmi \
+    genlex.cmi
+genlex.p.cmx : string.p.cmx stream.p.cmx list.p.cmx hashtbl.p.cmx char.p.cmx bytes.p.cmx \
+    genlex.cmi
 hashtbl.cmo : sys.cmi string.cmi random.cmi obj.cmi lazy.cmi array.cmi \
     hashtbl.cmi
 hashtbl.p.cmx : sys.p.cmx string.p.cmx random.p.cmx obj.p.cmx lazy.p.cmx array.p.cmx \
@@ -202,16 +217,16 @@ int64.cmo : pervasives.cmi int64.cmi
 int64.p.cmx : pervasives.p.cmx int64.cmi
 lazy.cmo : obj.cmi camlinternalLazy.cmi lazy.cmi
 lazy.p.cmx : obj.p.cmx camlinternalLazy.p.cmx lazy.cmi
-lexing.cmo : sys.cmi string.cmi array.cmi lexing.cmi
-lexing.p.cmx : sys.p.cmx string.p.cmx array.p.cmx lexing.cmi
+lexing.cmo : sys.cmi string.cmi bytes.cmi array.cmi lexing.cmi
+lexing.p.cmx : sys.p.cmx string.p.cmx bytes.p.cmx array.p.cmx lexing.cmi
 list.cmo : list.cmi
 list.p.cmx : list.cmi
 listLabels.cmo : list.cmi listLabels.cmi
 listLabels.p.cmx : list.p.cmx listLabels.cmi
 map.cmo : map.cmi
 map.p.cmx : map.cmi
-marshal.cmo : string.cmi marshal.cmi
-marshal.p.cmx : string.p.cmx marshal.cmi
+marshal.cmo : obj.cmi bytes.cmi marshal.cmi
+marshal.p.cmx : obj.p.cmx bytes.p.cmx marshal.cmi
 moreLabels.cmo : set.cmi map.cmi hashtbl.cmi moreLabels.cmi
 moreLabels.p.cmx : set.p.cmx map.p.cmx hashtbl.p.cmx moreLabels.cmi
 nativeint.cmo : sys.cmi pervasives.cmi nativeint.cmi
@@ -226,10 +241,10 @@ pervasives.cmo : pervasives.cmi
 pervasives.p.cmx : pervasives.cmi
 printexc.cmo : printf.cmi obj.cmi buffer.cmi array.cmi printexc.cmi
 printexc.p.cmx : printf.p.cmx obj.p.cmx buffer.p.cmx array.p.cmx printexc.cmi
-printf.cmo : string.cmi obj.cmi list.cmi char.cmi buffer.cmi array.cmi \
-    printf.cmi
-printf.p.cmx : string.p.cmx obj.p.cmx list.p.cmx char.p.cmx buffer.p.cmx array.p.cmx \
-    printf.cmi
+printf.cmo : string.cmi obj.cmi list.cmi char.cmi bytes.cmi buffer.cmi \
+    array.cmi printf.cmi
+printf.p.cmx : string.p.cmx obj.p.cmx list.p.cmx char.p.cmx bytes.p.cmx buffer.p.cmx \
+    array.p.cmx printf.cmi
 queue.cmo : obj.cmi queue.cmi
 queue.p.cmx : obj.p.cmx queue.cmi
 random.cmo : string.cmi pervasives.cmi nativeint.cmi int64.cmi int32.cmi \
@@ -237,9 +252,9 @@ random.cmo : string.cmi pervasives.cmi nativeint.cmi int64.cmi int32.cmi \
 random.p.cmx : string.p.cmx pervasives.p.cmx nativeint.p.cmx int64.p.cmx int32.p.cmx \
     digest.p.cmx char.p.cmx array.p.cmx random.cmi
 scanf.cmo : string.cmi printf.cmi pervasives.cmi obj.cmi list.cmi \
-    hashtbl.cmi buffer.cmi array.cmi scanf.cmi
+    hashtbl.cmi bytes.cmi buffer.cmi array.cmi scanf.cmi
 scanf.p.cmx : string.p.cmx printf.p.cmx pervasives.p.cmx obj.p.cmx list.p.cmx \
-    hashtbl.p.cmx buffer.p.cmx array.p.cmx scanf.cmi
+    hashtbl.p.cmx bytes.p.cmx buffer.p.cmx array.p.cmx scanf.cmi
 set.cmo : list.cmi set.cmi
 set.p.cmx : list.p.cmx set.cmi
 sort.cmo : array.cmi sort.cmi
@@ -252,10 +267,10 @@ stdLabels.p.cmx : stringLabels.p.cmx listLabels.p.cmx arrayLabels.p.cmx \
     stdLabels.cmi
 std_exit.cmo :
 std_exit.p.cmx :
-stream.cmo : string.cmi obj.cmi list.cmi lazy.cmi stream.cmi
-stream.p.cmx : string.p.cmx obj.p.cmx list.p.cmx lazy.p.cmx stream.cmi
-string.cmo : pervasives.cmi list.cmi char.cmi string.cmi
-string.p.cmx : pervasives.p.cmx list.p.cmx char.p.cmx string.cmi
+stream.cmo : string.cmi obj.cmi list.cmi lazy.cmi bytes.cmi stream.cmi
+stream.p.cmx : string.p.cmx obj.p.cmx list.p.cmx lazy.p.cmx bytes.p.cmx stream.cmi
+string.cmo : pervasives.cmi obj.cmi bytes.cmi string.cmi
+string.p.cmx : pervasives.p.cmx obj.p.cmx bytes.p.cmx string.cmi
 stringLabels.cmo : string.cmi stringLabels.cmi
 stringLabels.p.cmx : string.p.cmx stringLabels.cmi
 sys.cmo : sys.cmi
diff --git a/stdlib/Makefile.shared b/stdlib/Makefile.shared
index e4fee75d3c..65248cd10c 100755
--- a/stdlib/Makefile.shared
+++ b/stdlib/Makefile.shared
@@ -15,13 +15,14 @@ include ../config/Makefile
 RUNTIME=../boot/ocamlrun
 COMPILER=../ocamlc
 CAMLC=$(RUNTIME) $(COMPILER)
-COMPFLAGS=-strict-sequence -w +33..39 -g -warn-error A -bin-annot -nostdlib
+COMPFLAGS=-strict-sequence -w +33..39 -g -warn-error A -bin-annot -nostdlib \
+          -safe-string
 OPTCOMPILER=../ocamlopt
 CAMLOPT=$(RUNTIME) $(OPTCOMPILER)
 CAMLDEP=../boot/ocamlrun ../tools/ocamldep
 
 OBJS=pervasives.cmo $(OTHERS)
-OTHERS=array.cmo list.cmo char.cmo string.cmo sys.cmo \
+OTHERS=array.cmo list.cmo char.cmo bytes.cmo string.cmo sys.cmo \
   sort.cmo marshal.cmo obj.cmo \
   int32.cmo int64.cmo nativeint.cmo \
   lexing.cmo parsing.cmo \
@@ -33,7 +34,8 @@ OTHERS=array.cmo list.cmo char.cmo string.cmo sys.cmo \
   camlinternalOO.cmo oo.cmo camlinternalMod.cmo \
   genlex.cmo weak.cmo \
   filename.cmo complex.cmo \
-  arrayLabels.cmo listLabels.cmo stringLabels.cmo moreLabels.cmo stdLabels.cmo
+  arrayLabels.cmo listLabels.cmo bytesLabels.cmo \
+  stringLabels.cmo moreLabels.cmo stdLabels.cmo
 
 all: stdlib.cma std_exit.cmo camlheader camlheader_ur
 
diff --git a/stdlib/StdlibModules b/stdlib/StdlibModules
index c5c8896ed0..a4552ad940 100644
--- a/stdlib/StdlibModules
+++ b/stdlib/StdlibModules
@@ -21,6 +21,8 @@ STDLIB_MODULES=\
   array \
   arrayLabels \
   buffer \
+  bytes \
+  bytesLabels \
   callback \
   camlinternalLazy \
   camlinternalMod \
diff --git a/stdlib/buffer.ml b/stdlib/buffer.ml
index 78a9e26116..2d6f691a27 100644
--- a/stdlib/buffer.ml
+++ b/stdlib/buffer.ml
@@ -14,41 +14,38 @@
 (* Extensible buffers *)
 
 type t =
- {mutable buffer : string;
+ {mutable buffer : bytes;
   mutable position : int;
   mutable length : int;
-  initial_buffer : string}
+  initial_buffer : bytes}
 
 let create n =
  let n = if n < 1 then 1 else n in
  let n = if n > Sys.max_string_length then Sys.max_string_length else n in
- let s = String.create n in
+ let s = Bytes.create n in
  {buffer = s; position = 0; length = n; initial_buffer = s}
 
-let contents b = String.sub b.buffer 0 b.position
+let contents b = Bytes.sub_string b.buffer 0 b.position
+let to_bytes b = Bytes.sub b.buffer 0 b.position
 
 let sub b ofs len =
   if ofs < 0 || len < 0 || ofs > b.position - len
   then invalid_arg "Buffer.sub"
-  else begin
-    let r = String.create len in
-    String.unsafe_blit b.buffer ofs r 0 len;
-    r
-  end
+  else Bytes.sub_string b.buffer ofs len
 ;;
 
 let blit src srcoff dst dstoff len =
   if len < 0 || srcoff < 0 || srcoff > src.position - len
-             || dstoff < 0 || dstoff > (String.length dst) - len
+             || dstoff < 0 || dstoff > (Bytes.length dst) - len
   then invalid_arg "Buffer.blit"
   else
-    String.blit src.buffer srcoff dst dstoff len
+    Bytes.blit src.buffer srcoff dst dstoff len
 ;;
 
 let nth b ofs =
   if ofs < 0 || ofs >= b.position then
    invalid_arg "Buffer.nth"
-  else String.unsafe_get b.buffer ofs
+  else Bytes.unsafe_get b.buffer ofs
 ;;
 
 let length b = b.position
@@ -57,7 +54,7 @@ let clear b = b.position <- 0
 
 let reset b =
   b.position <- 0; b.buffer <- b.initial_buffer;
-  b.length <- String.length b.buffer
+  b.length <- Bytes.length b.buffer
 
 let resize b more =
   let len = b.length in
@@ -68,34 +65,39 @@ let resize b more =
     then new_len := Sys.max_string_length
     else failwith "Buffer.add: cannot grow buffer"
   end;
-  let new_buffer = String.create !new_len in
-  String.blit b.buffer 0 new_buffer 0 b.position;
+  let new_buffer = Bytes.create !new_len in
+  Bytes.blit b.buffer 0 new_buffer 0 b.position;
   b.buffer <- new_buffer;
   b.length <- !new_len
 
 let add_char b c =
   let pos = b.position in
   if pos >= b.length then resize b 1;
-  String.unsafe_set b.buffer pos c;
+  Bytes.unsafe_set b.buffer pos c;
   b.position <- pos + 1
 
-let add_substring b s offset len =
-  if offset < 0 || len < 0 || offset > String.length s - len
-  then invalid_arg "Buffer.add_substring";
+let add_subbytes b s offset len =
+  if offset < 0 || len < 0 || offset > Bytes.length s - len
+  then invalid_arg "Buffer.add_subbytes";
   let new_position = b.position + len in
   if new_position > b.length then resize b len;
-  String.unsafe_blit s offset b.buffer b.position len;
+  Bytes.unsafe_blit s offset b.buffer b.position len;
   b.position <- new_position
 
-let add_string b s =
-  let len = String.length s in
+let add_substring b s offset len =
+  add_subbytes b (Bytes.unsafe_of_string s) offset len
+
+let add_bytes b s =
+  let len = Bytes.length s in
   let new_position = b.position + len in
   if new_position > b.length then resize b len;
-  String.unsafe_blit s 0 b.buffer b.position len;
+  Bytes.unsafe_blit s 0 b.buffer b.position len;
   b.position <- new_position
 
+let add_string b s = add_bytes b (Bytes.unsafe_of_string s)
+
 let add_buffer b bs =
-  add_substring b bs.buffer 0 bs.position
+  add_subbytes b bs.buffer 0 bs.position
 
 let add_channel b ic len =
   if len < 0 || len > Sys.max_string_length then   (* PR#5004 *)
diff --git a/stdlib/buffer.mli b/stdlib/buffer.mli
index c50c98792b..855a061667 100644
--- a/stdlib/buffer.mli
+++ b/stdlib/buffer.mli
@@ -11,9 +11,9 @@
 (*                                                                     *)
 (***********************************************************************)
 
-(** Extensible string buffers.
+(** Extensible buffers.
 
-   This module implements string buffers that automatically expand
+   This module implements buffers that automatically expand
    as necessary.  It provides accumulative concatenation of strings
    in quasi-linear time (instead of quadratic time when strings are
    concatenated pairwise).
@@ -24,8 +24,8 @@ type t
 
 val create : int -> t
 (** [create n] returns a fresh buffer, initially empty.
-   The [n] parameter is the initial size of the internal string
-   that holds the buffer contents. That string is automatically
+   The [n] parameter is the initial size of the internal byte sequence
+   that holds the buffer contents. That byte sequence is automatically
    reallocated when more than [n] characters are stored in the buffer,
    but shrinks back to [n] characters when [reset] is called.
    For best performance, [n] should be of the same order of magnitude
@@ -40,20 +40,24 @@ val contents : t -> string
 (** Return a copy of the current contents of the buffer.
    The buffer itself is unchanged. *)
 
+val to_bytes : t -> bytes
+(** Return a copy of the current contents of the buffer.
+   The buffer itself is unchanged. *)
+
 val sub : t -> int -> int -> string
-(** [Buffer.sub b off len] returns (a copy of) the substring of the
+(** [Buffer.sub b off len] returns (a copy of) the bytes from the
 current contents of the buffer [b] starting at offset [off] of length
 [len] bytes. May raise [Invalid_argument] if out of bounds request. The
 buffer itself is unaffected. *)
 
-val blit : t -> int -> string -> int -> int -> unit
+val blit : t -> int -> bytes -> int -> int -> unit
 (** [Buffer.blit src srcoff dst dstoff len] copies [len] characters from
    the current contents of the buffer [src], starting at offset [srcoff]
-   to string [dst], starting at character [dstoff].
+   to [dst], starting at character [dstoff].
 
    Raise [Invalid_argument] if [srcoff] and [len] do not designate a valid
-   substring of [src], or if [dstoff] and [len] do not designate a valid
-   substring of [dst].
+   range of [src], or if [dstoff] and [len] do not designate a valid
+   range of [dst].
    @since 3.11.2
 *)
 
@@ -68,8 +72,8 @@ val clear : t -> unit
 (** Empty the buffer. *)
 
 val reset : t -> unit
-(** Empty the buffer and deallocate the internal string holding the
-   buffer contents, replacing it with the initial internal string
+(** Empty the buffer and deallocate the internal byte sequence holding the
+   buffer contents, replacing it with the initial internal byte sequence
    of length [n] that was allocated by {!Buffer.create} [n].
    For long-lived buffers that may have grown a lot, [reset] allows
    faster reclamation of the space used by the buffer. *)
@@ -80,10 +84,17 @@ val add_char : t -> char -> unit
 val add_string : t -> string -> unit
 (** [add_string b s] appends the string [s] at the end of the buffer [b]. *)
 
+val add_bytes : t -> bytes -> unit
+(** [add_string b s] appends the string [s] at the end of the buffer [b]. *)
+
 val add_substring : t -> string -> int -> int -> unit
 (** [add_substring b s ofs len] takes [len] characters from offset
    [ofs] in string [s] and appends them at the end of the buffer [b]. *)
 
+val add_subbytes : t -> bytes -> int -> int -> unit
+(** [add_substring b s ofs len] takes [len] characters from offset
+   [ofs] in byte sequence [s] and appends them at the end of the buffer [b]. *)
+
 val add_substitute : t -> (string -> string) -> string -> unit
 (** [add_substitute b f s] appends the string pattern [s] at the end
    of the buffer [b] with substitution.
diff --git a/stdlib/bytes.ml b/stdlib/bytes.ml
new file mode 100644
index 0000000000..e405f17274
--- /dev/null
+++ b/stdlib/bytes.ml
@@ -0,0 +1,211 @@
+(***********************************************************************)
+(*                                                                     *)
+(*                                OCaml                                *)
+(*                                                                     *)
+(*            Xavier Leroy, projet Cristal, INRIA Rocquencourt         *)
+(*                                                                     *)
+(*  Copyright 1996 Institut National de Recherche en Informatique et   *)
+(*  en Automatique.  All rights reserved.  This file is distributed    *)
+(*  under the terms of the GNU Library General Public License, with    *)
+(*  the special exception on linking described in file ../LICENSE.     *)
+(*                                                                     *)
+(***********************************************************************)
+
+(* Byte sequence operations *)
+
+external length : bytes -> int = "%string_length"
+external get : bytes -> int -> char = "%string_safe_get"
+external set : bytes -> int -> char -> unit = "%string_safe_set"
+external create : int -> bytes = "caml_create_string"
+external unsafe_get : bytes -> int -> char = "%string_unsafe_get"
+external unsafe_set : bytes -> int -> char -> unit = "%string_unsafe_set"
+external unsafe_blit : bytes -> int -> bytes -> int -> int -> unit
+                     = "caml_blit_string" "noalloc"
+external unsafe_fill : bytes -> int -> int -> char -> unit
+                     = "caml_fill_string" "noalloc"
+external unsafe_to_string : bytes -> string = "%identity"
+external unsafe_of_string : string -> bytes = "%identity"
+
+let make n c =
+  let s = create n in
+  unsafe_fill s 0 n c;
+  s
+
+let empty = create 0;;
+
+let copy s =
+  let len = length s in
+  let r = create len in
+  unsafe_blit s 0 r 0 len;
+  r
+
+let to_string b = unsafe_to_string (copy b)
+let of_string s = copy (unsafe_of_string s)
+
+let sub s ofs len =
+  if ofs < 0 || len < 0 || ofs > length s - len
+  then invalid_arg "Bytes.sub"
+  else begin
+    let r = create len in
+    unsafe_blit s ofs r 0 len;
+    r
+  end
+
+let sub_string b ofs len = unsafe_to_string (sub b ofs len)
+
+let fill s ofs len c =
+  if ofs < 0 || len < 0 || ofs > length s - len
+  then invalid_arg "Bytes.fill"
+  else unsafe_fill s ofs len c
+
+let blit s1 ofs1 s2 ofs2 len =
+  if len < 0 || ofs1 < 0 || ofs1 > length s1 - len
+             || ofs2 < 0 || ofs2 > length s2 - len
+  then invalid_arg "Bytes.blit"
+  else unsafe_blit s1 ofs1 s2 ofs2 len
+
+let iter f a =
+  for i = 0 to length a - 1 do f(unsafe_get a i) done
+
+let iteri f a =
+  for i = 0 to length a - 1 do f i (unsafe_get a i) done
+
+let concat sep l =
+  match l with
+    [] -> empty
+  | hd :: tl ->
+      let num = ref 0 and len = ref 0 in
+      List.iter (fun s -> incr num; len := !len + length s) l;
+      let r = create (!len + length sep * (!num - 1)) in
+      unsafe_blit hd 0 r 0 (length hd);
+      let pos = ref(length hd) in
+      List.iter
+        (fun s ->
+          unsafe_blit sep 0 r !pos (length sep);
+          pos := !pos + length sep;
+          unsafe_blit s 0 r !pos (length s);
+          pos := !pos + length s)
+        tl;
+      r
+
+external is_printable: char -> bool = "caml_is_printable"
+external char_code: char -> int = "%identity"
+external char_chr: int -> char = "%identity"
+
+let is_space = function
+  | ' ' | '\012' | '\n' | '\r' | '\t' -> true
+  | _ -> false
+
+let trim s =
+  let len = length s in
+  let i = ref 0 in
+  while !i < len && is_space (unsafe_get s !i) do
+    incr i
+  done;
+  let j = ref (len - 1) in
+  while !j >= !i && is_space (unsafe_get s !j) do
+    decr j
+  done;
+  if !j >= !i then
+    sub s !i (!j - !i + 1)
+  else
+    empty
+
+let escaped s =
+  let n = ref 0 in
+  for i = 0 to length s - 1 do
+    n := !n +
+      (match unsafe_get s i with
+       | '"' | '\\' | '\n' | '\t' | '\r' | '\b' -> 2
+       | c -> if is_printable c then 1 else 4)
+  done;
+  if !n = length s then copy s else begin
+    let s' = create !n in
+    n := 0;
+    for i = 0 to length s - 1 do
+      begin match unsafe_get s i with
+      | ('"' | '\\') as c ->
+          unsafe_set s' !n '\\'; incr n; unsafe_set s' !n c
+      | '\n' ->
+          unsafe_set s' !n '\\'; incr n; unsafe_set s' !n 'n'
+      | '\t' ->
+          unsafe_set s' !n '\\'; incr n; unsafe_set s' !n 't'
+      | '\r' ->
+          unsafe_set s' !n '\\'; incr n; unsafe_set s' !n 'r'
+      | '\b' ->
+          unsafe_set s' !n '\\'; incr n; unsafe_set s' !n 'b'
+      | c ->
+          if is_printable c then
+            unsafe_set s' !n c
+          else begin
+            let a = char_code c in
+            unsafe_set s' !n '\\';
+            incr n;
+            unsafe_set s' !n (char_chr (48 + a / 100));
+            incr n;
+            unsafe_set s' !n (char_chr (48 + (a / 10) mod 10));
+            incr n;
+            unsafe_set s' !n (char_chr (48 + a mod 10))
+          end
+      end;
+      incr n
+    done;
+    s'
+  end
+
+let map f s =
+  let l = length s in
+  if l = 0 then s else begin
+    let r = create l in
+    for i = 0 to l - 1 do unsafe_set r i (f(unsafe_get s i)) done;
+    r
+  end
+
+let uppercase s = map Char.uppercase s
+let lowercase s = map Char.lowercase s
+
+let apply1 f s =
+  if length s = 0 then s else begin
+    let r = copy s in
+    unsafe_set r 0 (f(unsafe_get s 0));
+    r
+  end
+
+let capitalize s = apply1 Char.uppercase s
+let uncapitalize s = apply1 Char.lowercase s
+
+let rec index_rec s lim i c =
+  if i >= lim then raise Not_found else
+  if unsafe_get s i = c then i else index_rec s lim (i + 1) c;;
+
+let index s c = index_rec s (length s) 0 c;;
+
+let index_from s i c =
+  let l = length s in
+  if i < 0 || i > l then invalid_arg "Bytes.index_from" else
+  index_rec s l i c;;
+
+let rec rindex_rec s i c =
+  if i < 0 then raise Not_found else
+  if unsafe_get s i = c then i else rindex_rec s (i - 1) c;;
+
+let rindex s c = rindex_rec s (length s - 1) c;;
+
+let rindex_from s i c =
+  if i < -1 || i >= length s then invalid_arg "Bytes.rindex_from" else
+  rindex_rec s i c;;
+
+let contains_from s i c =
+  let l = length s in
+  if i < 0 || i > l then invalid_arg "Bytes.contains_from" else
+  try ignore (index_rec s l i c); true with Not_found -> false;;
+
+let contains s c = contains_from s 0 c;;
+
+let rcontains_from s i c =
+  if i < 0 || i >= length s then invalid_arg "Bytes.rcontains_from" else
+  try ignore (rindex_rec s i c); true with Not_found -> false;;
+
+type t = bytes
+
+let compare (x: t) (y: t) = Pervasives.compare x y
diff --git a/stdlib/bytes.mli b/stdlib/bytes.mli
new file mode 100644
index 0000000000..0367d52bb7
--- /dev/null
+++ b/stdlib/bytes.mli
@@ -0,0 +1,226 @@
+(***********************************************************************)
+(*                                                                     *)
+(*                                OCaml                                *)
+(*                                                                     *)
+(*            Xavier Leroy, projet Cristal, INRIA Rocquencourt         *)
+(*                                                                     *)
+(*  Copyright 1996 Institut National de Recherche en Informatique et   *)
+(*  en Automatique.  All rights reserved.  This file is distributed    *)
+(*  under the terms of the GNU Library General Public License, with    *)
+(*  the special exception on linking described in file ../LICENSE.     *)
+(*                                                                     *)
+(***********************************************************************)
+
+(** Byte sequence operations.
+
+   A byte sequence is a mutable data structure that contains a
+   fixed-length sequence of bytes. Each byte can be indexed in
+   constant time for reading or writing.
+
+   Given a byte sequence [s] of length [l], we can access each of the
+   [l] bytes of [s] via its index in the sequence. Indexes start at
+   [0], and we will call an index valid in [s] if it falls within the
+   range [[0...l-1]] (inclusive). A position is the point between two
+   bytes or at the beginning or end of the sequence.  We call a
+   position valid in [s] if it falls within the range [[0...l]]
+   (inclusive). Note that the byte at index [n] is between positions
+   [n] and [n+1].
+
+   Two parameters [start] and [len] are said to designate a valid
+   range of [s] if [len >= 0] and [start] and [start+len] are valid
+   positions in [s].
+
+   Byte sequences can be modified in place, for instance via the [set]
+   and [blit] functions described below.  See also strings (module
+   {!String}), which are almost the same data structure, but cannot be
+   modified in place.
+
+   Bytes are represented by the OCaml type [char].
+
+   @since 4.02.0
+ *)
+
+external length : bytes -> int = "%string_length"
+(** Return the length (number of bytes) of the argument. *)
+
+external get : bytes -> int -> char = "%string_safe_get"
+(** [get s n] returns the byte at index [n] in argument [s].
+
+    Raise [Invalid_argument] if [n] not a valid index in [s]. *)
+
+external set : bytes -> int -> char -> unit = "%string_safe_set"
+(** [set s n c] modifies [s] in place, replacing the byte at index [n]
+    with [c].
+
+    Raise [Invalid_argument] if [n] is not a valid index in [s]. *)
+
+external create : int -> bytes = "caml_create_string"
+(** [create n] returns a new byte sequence of length [n]. The
+    sequence is uninitialized and contains arbitrary bytes.
+
+    Raise [Invalid_argument] if [n < 0] or [n > ]{!Sys.max_string_length}. *)
+
+val make : int -> char -> bytes
+(** [make n c] returns a new byte sequence of length [n], filled with
+    the byte [c].
+
+    Raise [Invalid_argument] if [n < 0] or [n > ]{!Sys.max_string_length}. *)
+
+val empty : bytes
+(** A byte sequence of size 0. *)
+
+val copy : bytes -> bytes
+(** Return a new byte sequence that contains the same bytes as the
+    argument. *)
+
+val of_string : string -> bytes
+(** Return a new byte sequence that contains the same bytes as the
+    given string. *)
+
+val to_string : bytes -> string
+(** Return a new string that contains the same bytes as the given byte
+    sequence. *)
+
+val sub : bytes -> int -> int -> bytes
+(** [sub s start len] returns a new byte sequence of length [len],
+    containing the subsequence of [s] that starts at position [start]
+    and has length [len].
+
+    Raise [Invalid_argument] if [start] and [len] do not designate a
+    valid range of [s]. *)
+
+val sub_string : bytes -> int -> int -> string
+(** Same as [sub] but return a string instead of a byte sequence. *)
+
+val fill : bytes -> int -> int -> char -> unit
+(** [fill s start len c] modifies [s] in place, replacing [len]
+    characters with [c], starting at [start].
+
+    Raise [Invalid_argument] if [start] and [len] do not designate a
+    valid range of [s]. *)
+
+val blit : bytes -> int -> bytes -> int -> int -> unit
+(** [blit src srcoff dst dstoff len] copies [len] bytes from sequence
+    [src], starting at index [srcoff], to sequence [dst], starting at
+    index [dstoff]. It works correctly even if [src] and [dst] are the
+    same byte sequence, and the source and destination intervals
+    overlap.
+
+    Raise [Invalid_argument] if [srcoff] and [len] do not
+    designate a valid range of [src], or if [dstoff] and [len]
+    do not designate a valid range of [dst]. *)
+
+val concat : bytes -> bytes list -> bytes
+(** [concat sep sl] concatenates the list of byte sequences [sl],
+    inserting the separator byte sequence [sep] between each, and
+    returns the result as a new byte sequence. *)
+
+val iter : (char -> unit) -> bytes -> unit
+(** [iter f s] applies function [f] in turn to all the bytes of [s].
+    It is equivalent to [f (get s 0); f (get s 1); ...; f (get s
+    (length s - 1)); ()]. *)
+
+val iteri : (int -> char -> unit) -> bytes -> unit
+(** Same as {!Bytes.iter}, but the function is applied to the index of
+    the byte as first argument and the byte itself as second
+    argument. *)
+
+val map : (char -> char) -> bytes -> bytes
+(** [map f s] applies function [f] in turn to all the bytes of [s] and
+    stores the resulting bytes in a new sequence that is returned as
+    the result. *)
+
+val trim : bytes -> bytes
+(** Return a copy of the argument, without leading and trailing
+    whitespace. The bytes regarded as whitespace are the ASCII
+    characters [' '], ['\012'], ['\n'], ['\r'], and ['\t']. *)
+
+val escaped : bytes -> bytes
+(** Return a copy of the argument, with special characters represented
+    by escape sequences, following the lexical conventions of OCaml. *)
+
+val index : bytes -> char -> int
+(** [index s c] returns the index of the first occurrence of byte [c]
+    in [s].
+
+    Raise [Not_found] if [c] does not occur in [s]. *)
+
+val rindex : bytes -> char -> int
+(** [rindex s c] returns the index of the last occurrence of byte [c]
+    in [s].
+
+    Raise [Not_found] if [c] does not occur in [s]. *)
+
+val index_from : bytes -> int -> char -> int
+(** [index_from s i c] returns the index of the first occurrence of
+    byte [c] in [s] after position [i].  [Bytes.index s c] is
+    equivalent to [Bytes.index_from s 0 c].
+
+    Raise [Invalid_argument] if [i] is not a valid position in [s].
+    Raise [Not_found] if [c] does not occur in [s] after position [i]. *)
+
+val rindex_from : bytes -> int -> char -> int
+(** [rindex_from s i c] returns the index of the last occurrence of
+    byte [c] in [s] before position [i+1].  [rindex s c] is equivalent
+    to [rindex_from s (Bytes.length s - 1) c].
+
+    Raise [Invalid_argument] if [i+1] is not a valid position in [s].
+    Raise [Not_found] if [c] does not occur in [s] before position [i+1]. *)
+
+val contains : bytes -> char -> bool
+(** [contains s c] tests if byte [c] appears in [s]. *)
+
+val contains_from : bytes -> int -> char -> bool
+(** [contains_from s start c] tests if byte [c] appears in [s] after
+    position [start].  [contains s c] is equivalent to [contains_from
+    s 0 c].
+
+    Raise [Invalid_argument] if [start] is not a valid position in [s]. *)
+
+val rcontains_from : bytes -> int -> char -> bool
+(** [rcontains_from s stop c] tests if byte [c] appears in [s] before
+    position [stop+1].
+
+    Raise [Invalid_argument] if [stop < 0] or [stop+1] is not a valid
+    position in [s]. *)
+
+val uppercase : bytes -> bytes
+(** Return a copy of the argument, with all lowercase letters
+    translated to uppercase, including accented letters of the ISO
+    Latin-1 (8859-1) character set. *)
+
+val lowercase : bytes -> bytes
+(** Return a copy of the argument, with all uppercase letters
+    translated to lowercase, including accented letters of the ISO
+    Latin-1 (8859-1) character set. *)
+
+val capitalize : bytes -> bytes
+(** Return a copy of the argument, with the first byte set to
+    uppercase. *)
+
+val uncapitalize : bytes -> bytes
+(** Return a copy of the argument, with the first byte set to
+    lowercase. *)
+
+type t = bytes
+(** An alias for the type of byte sequences. *)
+
+val compare: t -> t -> int
+(** The comparison function for byte sequences, with the same
+    specification as {!Pervasives.compare}.  Along with the type [t],
+    this function [compare] allows the module [Bytes] to be passed as
+    argument to the functors {!Set.Make} and {!Map.Make}. *)
+
+(**/**)
+
+(* The following is for system use only. Do not call directly. *)
+
+external unsafe_get : bytes -> int -> char = "%string_unsafe_get"
+external unsafe_set : bytes -> int -> char -> unit = "%string_unsafe_set"
+external unsafe_blit :
+  bytes -> int -> bytes -> int -> int -> unit
+  = "caml_blit_string" "noalloc"
+external unsafe_fill :
+  bytes -> int -> int -> char -> unit = "caml_fill_string" "noalloc"
+external unsafe_to_string : bytes -> string = "%identity"
+external unsafe_of_string : string -> bytes = "%identity"
diff --git a/stdlib/bytesLabels.ml b/stdlib/bytesLabels.ml
new file mode 100644
index 0000000000..8ec8ec9e10
--- /dev/null
+++ b/stdlib/bytesLabels.ml
@@ -0,0 +1,16 @@
+(***********************************************************************)
+(*                                                                     *)
+(*                                OCaml                                *)
+(*                                                                     *)
+(*               Jacques Garrigue, Kyoto University RIMS               *)
+(*                                                                     *)
+(*  Copyright 2001 Institut National de Recherche en Informatique et   *)
+(*  en Automatique.  All rights reserved.  This file is distributed    *)
+(*  under the terms of the GNU Library General Public License, with    *)
+(*  the special exception on linking described in file ../LICENSE.     *)
+(*                                                                     *)
+(***********************************************************************)
+
+(* Module [BytesLabels]: labelled Bytes module *)
+
+include Bytes
diff --git a/stdlib/bytesLabels.mli b/stdlib/bytesLabels.mli
new file mode 100644
index 0000000000..e8eaaa9feb
--- /dev/null
+++ b/stdlib/bytesLabels.mli
@@ -0,0 +1,202 @@
+(***********************************************************************)
+(*                                                                     *)
+(*                                OCaml                                *)
+(*                                                                     *)
+(*            Xavier Leroy, projet Cristal, INRIA Rocquencourt         *)
+(*                                                                     *)
+(*  Copyright 1996 Institut National de Recherche en Informatique et   *)
+(*  en Automatique.  All rights reserved.  This file is distributed    *)
+(*  under the terms of the GNU Library General Public License, with    *)
+(*  the special exception on linking described in file ../LICENSE.     *)
+(*                                                                     *)
+(***********************************************************************)
+
+(** Byte sequence operations. *)
+
+external length : bytes -> int = "%string_length"
+(** Return the length (number of bytes) of the argument. *)
+
+external get : bytes -> int -> char = "%string_safe_get"
+(** [get s n] returns the byte at index [n] in argument [s].
+
+    Raise [Invalid_argument] if [n] not a valid index in [s]. *)
+
+
+external set : bytes -> int -> char -> unit = "%string_safe_set"
+(** [set s n c] modifies [s] in place, replacing the byte at index [n]
+    with [c].
+
+    Raise [Invalid_argument] if [n] is not a valid index in [s]. *)
+
+external create : int -> bytes = "caml_create_string"
+(** [create n] returns a new byte sequence of length [n]. The
+    sequence is uninitialized and contains arbitrary bytes.
+
+    Raise [Invalid_argument] if [n < 0] or [n > ]{!Sys.max_string_length}. *)
+
+val make : int -> char -> bytes
+(** [make n c] returns a new byte sequence of length [n], filled with
+    the byte [c].
+
+    Raise [Invalid_argument] if [n < 0] or [n > ]{!Sys.max_string_length}. *)
+
+val empty : bytes
+(** A byte sequence of size 0. *)
+
+val copy : bytes -> bytes
+(** Return a new byte sequence that contains the same bytes as the
+    argument. *)
+
+val of_string : string -> bytes
+(** Return a new byte sequence that contains the same bytes as the
+    given string. *)
+
+val to_string : bytes -> string
+(** Return a new string that contains the same bytes as the given byte
+    sequence. *)
+
+val sub : bytes -> pos:int -> len:int -> bytes
+(** [sub s start len] returns a new byte sequence of length [len],
+    containing the subsequence of [s] that starts at position [start]
+    and has length [len].
+
+    Raise [Invalid_argument] if [start] and [len] do not designate a
+    valid range of [s]. *)
+
+val sub_string : bytes -> int -> int -> string
+(** Same as [sub] but return a string instead of a byte sequence. *)
+
+val fill : bytes -> pos:int -> len:int -> char -> unit
+(** [fill s start len c] modifies [s] in place, replacing [len]
+    characters with [c], starting at [start].
+
+    Raise [Invalid_argument] if [start] and [len] do not designate a
+    valid range of [s]. *)
+
+val blit :
+  src:bytes -> src_pos:int -> dst:bytes -> dst_pos:int -> len:int
+  -> unit
+(** [blit src srcoff dst dstoff len] copies [len] bytes from sequence
+    [src], starting at index [srcoff], to sequence [dst], starting at
+    index [dstoff]. It works correctly even if [src] and [dst] are the
+    same byte sequence, and the source and destination intervals
+    overlap.
+
+    Raise [Invalid_argument] if [srcoff] and [len] do not
+    designate a valid range of [src], or if [dstoff] and [len]
+    do not designate a valid range of [dst]. *)
+
+val concat : sep:bytes -> bytes list -> bytes
+(** [concat sep sl] concatenates the list of byte sequences [sl],
+    inserting the separator byte sequence [sep] between each, and
+    returns the result as a new byte sequence. *)
+
+val iter : f:(char -> unit) -> bytes -> unit
+(** [iter f s] applies function [f] in turn to all the bytes of [s].
+    It is equivalent to [f (get s 0); f (get s 1); ...; f (get s
+    (length s - 1)); ()]. *)
+
+val iteri : f:(int -> char -> unit) -> bytes -> unit
+(** Same as {!Bytes.iter}, but the function is applied to the index of
+    the byte as first argument and the byte itself as second
+    argument. *)
+
+val map : f:(char -> char) -> bytes -> bytes
+(** [map f s] applies function [f] in turn to all the bytes of [s] and
+    stores the resulting bytes in a new sequence that is returned as
+    the result. *)
+
+val trim : bytes -> bytes
+(** Return a copy of the argument, without leading and trailing
+    whitespace. The bytes regarded as whitespace are the ASCII
+    characters [' '], ['\012'], ['\n'], ['\r'], and ['\t']. *)
+
+val escaped : bytes -> bytes
+(** Return a copy of the argument, with special characters represented
+    by escape sequences, following the lexical conventions of OCaml. *)
+
+val index : bytes -> char -> int
+(** [index s c] returns the index of the first occurrence of byte [c]
+    in [s].
+
+    Raise [Not_found] if [c] does not occur in [s]. *)
+
+val rindex : bytes -> char -> int
+(** [rindex s c] returns the index of the last occurrence of byte [c]
+    in [s].
+
+    Raise [Not_found] if [c] does not occur in [s]. *)
+
+val index_from : bytes -> int -> char -> int
+(** [index_from s i c] returns the index of the first occurrence of
+    byte [c] in [s] after position [i].  [Bytes.index s c] is
+    equivalent to [Bytes.index_from s 0 c].
+
+    Raise [Invalid_argument] if [i] is not a valid position in [s].
+    Raise [Not_found] if [c] does not occur in [s] after position [i]. *)
+
+val rindex_from : bytes -> int -> char -> int
+(** [rindex_from s i c] returns the index of the last occurrence of
+    byte [c] in [s] before position [i+1].  [rindex s c] is equivalent
+    to [rindex_from s (Bytes.length s - 1) c].
+
+    Raise [Invalid_argument] if [i+1] is not a valid position in [s].
+    Raise [Not_found] if [c] does not occur in [s] before position [i+1]. *)
+
+val contains : bytes -> char -> bool
+(** [contains s c] tests if byte [c] appears in [s]. *)
+
+val contains_from : bytes -> int -> char -> bool
+(** [contains_from s start c] tests if byte [c] appears in [s] after
+    position [start].  [contains s c] is equivalent to [contains_from
+    s 0 c].
+
+    Raise [Invalid_argument] if [start] is not a valid position in [s]. *)
+
+val rcontains_from : bytes -> int -> char -> bool
+(** [rcontains_from s stop c] tests if byte [c] appears in [s] before
+    position [stop+1].
+
+    Raise [Invalid_argument] if [stop < 0] or [stop+1] is not a valid
+    position in [s]. *)
+
+val uppercase : bytes -> bytes
+(** Return a copy of the argument, with all lowercase letters
+    translated to uppercase, including accented letters of the ISO
+    Latin-1 (8859-1) character set. *)
+
+val lowercase : bytes -> bytes
+(** Return a copy of the argument, with all uppercase letters
+    translated to lowercase, including accented letters of the ISO
+    Latin-1 (8859-1) character set. *)
+
+val capitalize : bytes -> bytes
+(** Return a copy of the argument, with the first byte set to
+    uppercase. *)
+
+val uncapitalize : bytes -> bytes
+(** Return a copy of the argument, with the first byte set to
+    lowercase. *)
+
+type t = bytes
+(** An alias for the type of byte sequences. *)
+
+val compare: t -> t -> int
+(** The comparison function for byte sequences, with the same
+    specification as {!Pervasives.compare}.  Along with the type [t],
+    this function [compare] allows the module [Bytes] to be passed as
+    argument to the functors {!Set.Make} and {!Map.Make}. *)
+
+(**/**)
+
+(* The following is for system use only. Do not call directly. *)
+
+external unsafe_get : bytes -> int -> char = "%string_unsafe_get"
+external unsafe_set : bytes -> int -> char -> unit = "%string_unsafe_set"
+external unsafe_blit :
+  src:bytes -> src_pos:int -> dst:bytes -> dst_pos:int -> len:int ->
+    unit = "caml_blit_string" "noalloc"
+external unsafe_fill :
+  bytes -> pos:int -> len:int -> char -> unit = "caml_fill_string" "noalloc"
+external unsafe_to_string : bytes -> string = "%identity"
+external unsafe_of_string : string -> bytes = "%identity"
diff --git a/stdlib/digest.ml b/stdlib/digest.ml
index 7c607ee1f8..e6b6b35898 100644
--- a/stdlib/digest.ml
+++ b/stdlib/digest.ml
@@ -35,24 +35,21 @@ let file filename =
   d
 
 let output chan digest =
-  output chan digest 0 16
+  output_string chan digest
 
-let input chan =
-  let digest = String.create 16 in
-  really_input chan digest 0 16;
-  digest
+let input chan = really_input_string chan 16
 
 let char_hex n =
   Char.unsafe_chr (n + if n < 10 then Char.code '0' else (Char.code 'a' - 10))
 
 let to_hex d =
-  let result = String.create 32 in
+  let result = Bytes.create 32 in
   for i = 0 to 15 do
     let x = Char.code d.[i] in
-    String.unsafe_set result (i*2) (char_hex (x lsr 4));
-    String.unsafe_set result (i*2+1) (char_hex (x land 0x0f));
+    Bytes.unsafe_set result (i*2) (char_hex (x lsr 4));
+    Bytes.unsafe_set result (i*2+1) (char_hex (x land 0x0f));
   done;
-  result
+  Bytes.unsafe_to_string result
 
 let from_hex s =
   if String.length s <> 32 then raise (Invalid_argument "Digest.from_hex");
@@ -64,8 +61,8 @@ let from_hex s =
     | _ -> raise (Invalid_argument "Digest.from_hex")
   in
   let byte i = digit s.[i] lsl 4 + digit s.[i+1] in
-  let result = String.create 16 in
+  let result = Bytes.create 16 in
   for i = 0 to 15 do
-    result.[i] <- Char.chr (byte (2 * i));
+    Bytes.set result i (Char.chr (byte (2 * i)));
   done;
-  result
+  Bytes.unsafe_to_string result
diff --git a/stdlib/format.ml b/stdlib/format.ml
index 02222932e4..18de7e24cf 100644
--- a/stdlib/format.ml
+++ b/stdlib/format.ml
@@ -657,9 +657,7 @@ let pp_print_bool state b = pp_print_string state (string_of_bool b);;
 
 (* To format a char. *)
 let pp_print_char state c =
-  let s = String.create 1 in
-  s.[0] <- c;
-  pp_print_as state 1 s
+  pp_print_as state 1 (String.make 1 c)
 ;;
 
 (* Opening boxes. *)
@@ -901,7 +899,7 @@ let rec display_blanks state n =
 ;;
 
 let pp_set_formatter_out_channel state os =
-  state.pp_out_string <- output os;
+  state.pp_out_string <- output_substring os;
   state.pp_out_flush <- (fun () -> flush os);
   state.pp_out_newline <- display_newline state;
   state.pp_out_spaces <- display_blanks state;
@@ -967,7 +965,7 @@ let make_formatter output flush =
 ;;
 
 let formatter_of_out_channel oc =
-  make_formatter (output oc) (fun () -> flush oc)
+  make_formatter (output_substring oc) (fun () -> flush oc)
 ;;
 
 let formatter_of_buffer b =
diff --git a/stdlib/genlex.ml b/stdlib/genlex.ml
index dc80727df2..4f52b18654 100644
--- a/stdlib/genlex.ml
+++ b/stdlib/genlex.ml
@@ -21,7 +21,7 @@ type token =
 
 (* The string buffering machinery *)
 
-let initial_buffer = String.create 32
+let initial_buffer = Bytes.create 32
 
 let buffer = ref initial_buffer
 let bufpos = ref 0
@@ -29,16 +29,16 @@ let bufpos = ref 0
 let reset_buffer () = buffer := initial_buffer; bufpos := 0
 
 let store c =
-  if !bufpos >= String.length !buffer then
-    begin
-      let newbuffer = String.create (2 * !bufpos) in
-      String.blit !buffer 0 newbuffer 0 !bufpos; buffer := newbuffer
-    end;
-  String.set !buffer !bufpos c;
+  if !bufpos >= Bytes.length !buffer then begin
+    let newbuffer = Bytes.create (2 * !bufpos) in
+    Bytes.blit !buffer 0 newbuffer 0 !bufpos;
+    buffer := newbuffer
+  end;
+  Bytes.set !buffer !bufpos c;
   incr bufpos
 
 let get_string () =
-  let s = String.sub !buffer 0 !bufpos in buffer := initial_buffer; s
+  let s = Bytes.sub_string !buffer 0 !bufpos in buffer := initial_buffer; s
 
 (* The lexer *)
 
diff --git a/stdlib/lexing.ml b/stdlib/lexing.ml
index 53748ad867..d2231fbe9b 100644
--- a/stdlib/lexing.ml
+++ b/stdlib/lexing.ml
@@ -29,7 +29,7 @@ let dummy_pos = {
 
 type lexbuf =
   { refill_buff : lexbuf -> unit;
-    mutable lex_buffer : string;
+    mutable lex_buffer : bytes;
     mutable lex_buffer_len : int;
     mutable lex_abs_pos : int;
     mutable lex_start_pos : int;
@@ -81,7 +81,7 @@ let new_engine tbl state buf =
 
 let lex_refill read_fun aux_buffer lexbuf =
   let read =
-    read_fun aux_buffer (String.length aux_buffer) in
+    read_fun aux_buffer (Bytes.length aux_buffer) in
   let n =
     if read > 0
     then read
@@ -90,16 +90,16 @@ let lex_refill read_fun aux_buffer lexbuf =
         <-------|---------------------|----------->
         |  junk |      valid data     |   junk    |
         ^       ^                     ^           ^
-        0    start_pos             buffer_end    String.length buffer
+        0    start_pos             buffer_end    Bytes.length buffer
   *)
-  if lexbuf.lex_buffer_len + n > String.length lexbuf.lex_buffer then begin
+  if lexbuf.lex_buffer_len + n > Bytes.length lexbuf.lex_buffer then begin
     (* There is not enough space at the end of the buffer *)
     if lexbuf.lex_buffer_len - lexbuf.lex_start_pos + n
-       <= String.length lexbuf.lex_buffer
+       <= Bytes.length lexbuf.lex_buffer
     then begin
       (* But there is enough space if we reclaim the junk at the beginning
          of the buffer *)
-      String.blit lexbuf.lex_buffer lexbuf.lex_start_pos
+      Bytes.blit lexbuf.lex_buffer lexbuf.lex_start_pos
                   lexbuf.lex_buffer 0
                   (lexbuf.lex_buffer_len - lexbuf.lex_start_pos)
     end else begin
@@ -107,12 +107,12 @@ let lex_refill read_fun aux_buffer lexbuf =
          space since n <= String.length aux_buffer <= String.length buffer.
          Watch out for string length overflow, though. *)
       let newlen =
-        min (2 * String.length lexbuf.lex_buffer) Sys.max_string_length in
+        min (2 * Bytes.length lexbuf.lex_buffer) Sys.max_string_length in
       if lexbuf.lex_buffer_len - lexbuf.lex_start_pos + n > newlen
       then failwith "Lexing.lex_refill: cannot grow buffer";
-      let newbuf = String.create newlen in
+      let newbuf = Bytes.create newlen in
       (* Copy the valid data to the beginning of the new buffer *)
-      String.blit lexbuf.lex_buffer lexbuf.lex_start_pos
+      Bytes.blit lexbuf.lex_buffer lexbuf.lex_start_pos
                   newbuf 0
                   (lexbuf.lex_buffer_len - lexbuf.lex_start_pos);
       lexbuf.lex_buffer <- newbuf
@@ -133,9 +133,7 @@ let lex_refill read_fun aux_buffer lexbuf =
     done
   end;
   (* There is now enough space at the end of the buffer *)
-  String.blit aux_buffer 0
-              lexbuf.lex_buffer lexbuf.lex_buffer_len
-              n;
+  Bytes.blit aux_buffer 0 lexbuf.lex_buffer lexbuf.lex_buffer_len n;
   lexbuf.lex_buffer_len <- lexbuf.lex_buffer_len + n
 
 let zero_pos = {
@@ -146,8 +144,8 @@ let zero_pos = {
 };;
 
 let from_function f =
-  { refill_buff = lex_refill f (String.create 512);
-    lex_buffer = String.create 1024;
+  { refill_buff = lex_refill f (Bytes.create 512);
+    lex_buffer = Bytes.create 1024;
     lex_buffer_len = 0;
     lex_abs_pos = 0;
     lex_start_pos = 0;
@@ -165,7 +163,8 @@ let from_channel ic =
 
 let from_string s =
   { refill_buff = (fun lexbuf -> lexbuf.lex_eof_reached <- true);
-    lex_buffer = s ^ "";
+    lex_buffer = Bytes.of_string s; (* have to make a copy for compatibility
+                                       with unsafe-string mode *)
     lex_buffer_len = String.length s;
     lex_abs_pos = 0;
     lex_start_pos = 0;
@@ -180,37 +179,31 @@ let from_string s =
 
 let lexeme lexbuf =
   let len = lexbuf.lex_curr_pos - lexbuf.lex_start_pos in
-  let s = String.create len in
-  String.unsafe_blit lexbuf.lex_buffer lexbuf.lex_start_pos s 0 len;
-  s
+  Bytes.sub_string lexbuf.lex_buffer lexbuf.lex_start_pos len
 
 let sub_lexeme lexbuf i1 i2 =
   let len = i2-i1 in
-  let s = String.create len in
-  String.unsafe_blit lexbuf.lex_buffer i1 s 0 len;
-  s
+  Bytes.sub_string lexbuf.lex_buffer i1 len
 
 let sub_lexeme_opt lexbuf i1 i2 =
   if i1 >= 0 then begin
     let len = i2-i1 in
-    let s = String.create len in
-    String.unsafe_blit lexbuf.lex_buffer i1 s 0 len;
-    Some s
+    Some (Bytes.sub_string lexbuf.lex_buffer i1 len)
   end else begin
     None
   end
 
-let sub_lexeme_char lexbuf i = lexbuf.lex_buffer.[i]
+let sub_lexeme_char lexbuf i = Bytes.get lexbuf.lex_buffer i
 
 let sub_lexeme_char_opt lexbuf i =
   if i >= 0 then
-    Some lexbuf.lex_buffer.[i]
+    Some (Bytes.get lexbuf.lex_buffer i)
   else
     None
 
 
 let lexeme_char lexbuf i =
-  String.get lexbuf.lex_buffer (lexbuf.lex_start_pos + i)
+  Bytes.get lexbuf.lex_buffer (lexbuf.lex_start_pos + i)
 
 let lexeme_start lexbuf = lexbuf.lex_start_p.pos_cnum;;
 let lexeme_end lexbuf = lexbuf.lex_curr_p.pos_cnum;;
diff --git a/stdlib/lexing.mli b/stdlib/lexing.mli
index 6d5406d693..30898670b7 100644
--- a/stdlib/lexing.mli
+++ b/stdlib/lexing.mli
@@ -46,7 +46,7 @@ val dummy_pos : position;;
 
 type lexbuf =
   { refill_buff : lexbuf -> unit;
-    mutable lex_buffer : string;
+    mutable lex_buffer : bytes;
     mutable lex_buffer_len : int;
     mutable lex_abs_pos : int;
     mutable lex_start_pos : int;
@@ -84,12 +84,12 @@ val from_string : string -> lexbuf
    the string. An end-of-input condition is generated when the
    end of the string is reached. *)
 
-val from_function : (string -> int -> int) -> lexbuf
+val from_function : (bytes -> int -> int) -> lexbuf
 (** Create a lexer buffer with the given function as its reading method.
    When the scanner needs more characters, it will call the given
-   function, giving it a character string [s] and a character
-   count [n]. The function should put [n] characters or less in [s],
-   starting at character number 0, and return the number of characters
+   function, giving it a byte sequence [s] and a byte
+   count [n]. The function should put [n] bytes or fewer in [s],
+   starting at index 0, and return the number of bytes
    provided. A return value of 0 means end of input. *)
 
 
diff --git a/stdlib/marshal.ml b/stdlib/marshal.ml
index 7a65a16a37..4f59a3ef21 100644
--- a/stdlib/marshal.ml
+++ b/stdlib/marshal.ml
@@ -19,35 +19,39 @@ type extern_flags =
 
 external to_channel: out_channel -> 'a -> extern_flags list -> unit
     = "caml_output_value"
+external to_bytes: 'a -> extern_flags list -> bytes
+    = "caml_output_value_to_string"
 external to_string: 'a -> extern_flags list -> string
     = "caml_output_value_to_string"
 external to_buffer_unsafe:
-      string -> int -> int -> 'a -> extern_flags list -> int
+      bytes -> int -> int -> 'a -> extern_flags list -> int
     = "caml_output_value_to_buffer"
 
 let to_buffer buff ofs len v flags =
-  if ofs < 0 || len < 0 || ofs > String.length buff - len
+  if ofs < 0 || len < 0 || ofs > Bytes.length buff - len
   then invalid_arg "Marshal.to_buffer: substring out of bounds"
   else to_buffer_unsafe buff ofs len v flags
 
 external from_channel: in_channel -> 'a = "caml_input_value"
-external from_string_unsafe: string -> int -> 'a
+external from_bytes_unsafe: bytes -> int -> 'a
                            = "caml_input_value_from_string"
-external data_size_unsafe: string -> int -> int = "caml_marshal_data_size"
+external data_size_unsafe: bytes -> int -> int = "caml_marshal_data_size"
 
 let header_size = 20
 let data_size buff ofs =
-  if ofs < 0 || ofs > String.length buff - header_size
+  if ofs < 0 || ofs > Bytes.length buff - header_size
   then invalid_arg "Marshal.data_size"
   else data_size_unsafe buff ofs
 let total_size buff ofs = header_size + data_size buff ofs
 
-let from_string buff ofs =
-  if ofs < 0 || ofs > String.length buff - header_size
-  then invalid_arg "Marshal.from_size"
+let from_bytes buff ofs =
+  if ofs < 0 || ofs > Bytes.length buff - header_size
+  then invalid_arg "Marshal.from_bytes"
   else begin
     let len = data_size_unsafe buff ofs in
-    if ofs > String.length buff - (header_size + len)
-    then invalid_arg "Marshal.from_string"
-    else from_string_unsafe buff ofs
+    if ofs > Bytes.length buff - (header_size + len)
+    then invalid_arg "Marshal.from_bytes"
+    else from_bytes_unsafe buff ofs
   end
+
+let from_string buff ofs = from_bytes (Bytes.unsafe_of_string buff) ofs
diff --git a/stdlib/marshal.mli b/stdlib/marshal.mli
index 1ab15230cb..1099773a39 100644
--- a/stdlib/marshal.mli
+++ b/stdlib/marshal.mli
@@ -108,19 +108,24 @@ val to_channel : out_channel -> 'a -> extern_flags list -> unit
    it has no effect if marshaling is performed on a 32-bit platform.
  *)
 
-external to_string :
-  'a -> extern_flags list -> string = "caml_output_value_to_string"
-(** [Marshal.to_string v flags] returns a string containing
-   the representation of [v] as a sequence of bytes.
+external to_bytes :
+  'a -> extern_flags list -> bytes = "caml_output_value_to_string"
+(** [Marshal.to_string v flags] returns a byte sequence containing
+   the representation of [v].
    The [flags] argument has the same meaning as for
    {!Marshal.to_channel}. *)
 
-val to_buffer : string -> int -> int -> 'a -> extern_flags list -> int
+external to_string :
+  'a -> extern_flags list -> string = "caml_output_value_to_string"
+(** Same as [to_bytes] but return the result as a string instead of
+    a byte sequence. *)
+
+val to_buffer : bytes -> int -> int -> 'a -> extern_flags list -> int
 (** [Marshal.to_buffer buff ofs len v flags] marshals the value [v],
-   storing its byte representation in the string [buff],
-   starting at character number [ofs], and writing at most
-   [len] characters.  It returns the number of characters
-   actually written to the string. If the byte representation
+   storing its byte representation in the sequence [buff],
+   starting at index [ofs], and writing at most
+   [len] bytes.  It returns the number of bytes
+   actually written to the sequence. If the byte representation
    of [v] does not fit in [len] characters, the exception [Failure]
    is raised. *)
 
@@ -130,36 +135,40 @@ val from_channel : in_channel -> 'a
    one of the [Marshal.to_*] functions, and reconstructs and
    returns the corresponding value.*)
 
-val from_string : string -> int -> 'a
-(** [Marshal.from_string buff ofs] unmarshals a structured value
+val from_bytes : bytes -> int -> 'a
+(** [Marshal.from_bytes buff ofs] unmarshals a structured value
    like {!Marshal.from_channel} does, except that the byte
    representation is not read from a channel, but taken from
    the string [buff], starting at position [ofs]. *)
 
+val from_string : string -> int -> 'a
+(** Same as [from_bytes] but take a string as argument instead of a
+    byte sequence. *)
+
 val header_size : int
 (** The bytes representing a marshaled value are composed of
    a fixed-size header and a variable-sized data part,
    whose size can be determined from the header.
-   {!Marshal.header_size} is the size, in characters, of the header.
-   {!Marshal.data_size}[ buff ofs] is the size, in characters,
+   {!Marshal.header_size} is the size, in bytes, of the header.
+   {!Marshal.data_size}[ buff ofs] is the size, in bytes,
    of the data part, assuming a valid header is stored in
    [buff] starting at position [ofs].
    Finally, {!Marshal.total_size} [buff ofs] is the total size,
-   in characters, of the marshaled value.
+   in bytes, of the marshaled value.
    Both {!Marshal.data_size} and {!Marshal.total_size} raise [Failure]
    if [buff], [ofs] does not contain a valid header.
 
    To read the byte representation of a marshaled value into
-   a string buffer, the program needs to read first
-   {!Marshal.header_size} characters into the buffer,
+   a byte sequence, the program needs to read first
+   {!Marshal.header_size} bytes into the sequence,
    then determine the length of the remainder of the
    representation using {!Marshal.data_size},
-   make sure the buffer is large enough to hold the remaining
-   data, then read it, and finally call {!Marshal.from_string}
+   make sure the sequence is large enough to hold the remaining
+   data, then read it, and finally call {!Marshal.from_bytes}
    to unmarshal the value. *)
 
-val data_size : string -> int -> int
+val data_size : bytes -> int -> int
 (** See {!Marshal.header_size}.*)
 
-val total_size : string -> int -> int
+val total_size : bytes -> int -> int
 (** See {!Marshal.header_size}.*)
diff --git a/stdlib/obj.ml b/stdlib/obj.ml
index a6f11586e8..b9fb76d9dd 100644
--- a/stdlib/obj.ml
+++ b/stdlib/obj.ml
@@ -33,9 +33,9 @@ external truncate : t -> int -> unit = "caml_obj_truncate"
 external add_offset : t -> Int32.t -> t = "caml_obj_add_offset"
 
 let marshal (obj : t) =
-  Marshal.to_string obj []
+  Marshal.to_bytes obj []
 let unmarshal str pos =
-  (Marshal.from_string str pos, pos + Marshal.total_size str pos)
+  (Marshal.from_bytes str pos, pos + Marshal.total_size str pos)
 
 let lazy_tag = 246
 let closure_tag = 247
diff --git a/stdlib/obj.mli b/stdlib/obj.mli
index 9a5bd721d5..b1dcc456f8 100644
--- a/stdlib/obj.mli
+++ b/stdlib/obj.mli
@@ -43,11 +43,11 @@ val infix_tag : int
 val forward_tag : int
 val no_scan_tag : int
 val abstract_tag : int
-val string_tag : int
+val string_tag : int   (* both [string] and [bytes] *)
 val double_tag : int
 val double_array_tag : int
 val custom_tag : int
-val final_tag : int  (* DEPRECATED *)
+val final_tag : int [@@ocaml.deprecated]
 
 val int_tag : int
 val out_of_heap_tag : int
@@ -56,5 +56,5 @@ val unaligned_tag : int   (* should never happen @since 3.11.0 *)
 (** The following two functions are deprecated.  Use module {!Marshal}
     instead. *)
 
-val marshal : t -> string
-val unmarshal : string -> int -> t * int
+val marshal : t -> bytes [@@ocaml.deprecated]
+val unmarshal : bytes -> int -> t * int [@@ocaml.deprecated]
diff --git a/stdlib/pervasives.ml b/stdlib/pervasives.ml
index 9f88480bfa..979f691f86 100644
--- a/stdlib/pervasives.ml
+++ b/stdlib/pervasives.ml
@@ -164,19 +164,24 @@ type fpclass =
   | FP_nan
 external classify_float : float -> fpclass = "caml_classify_float"
 
-(* String operations -- more in module String *)
+(* String and byte sequence operations -- more in modules String and Bytes *)
 
 external string_length : string -> int = "%string_length"
-external string_create : int -> string = "caml_create_string"
-external string_blit : string -> int -> string -> int -> int -> unit
+external bytes_length : bytes -> int = "%string_length"
+external bytes_create : int -> bytes = "caml_create_string"
+external string_blit : string -> int -> bytes -> int -> int -> unit
                      = "caml_blit_string" "noalloc"
+external bytes_blit : bytes -> int -> bytes -> int -> int -> unit
+                        = "caml_blit_string" "noalloc"
+external bytes_unsafe_to_string : bytes -> string = "%identity"
+external bytes_unsafe_of_string : string -> bytes = "%identity"
 
 let ( ^ ) s1 s2 =
   let l1 = string_length s1 and l2 = string_length s2 in
-  let s = string_create (l1 + l2) in
+  let s = bytes_create (l1 + l2) in
   string_blit s1 0 s 0 l1;
   string_blit s2 0 s l1 l2;
-  s
+  bytes_unsafe_to_string s
 
 (* Character operations -- more in module Char *)
 
@@ -219,16 +224,13 @@ let string_of_int n =
   format_int "%d" n
 
 external int_of_string : string -> int = "caml_int_of_string"
-
-module String = struct
-  external get : string -> int -> char = "%string_safe_get"
-end
+external string_get : string -> int -> char = "%string_safe_get"
 
 let valid_float_lexem s =
   let l = string_length s in
   let rec loop i =
     if i >= l then s ^ "." else
-    match s.[i] with
+    match string_get s i with
     | '0' .. '9' | '-' -> loop (i + 1)
     | _ -> s
   in
@@ -288,19 +290,25 @@ let flush_all () =
     | a :: l -> (try flush a with _ -> ()); iter l
   in iter (out_channels_list ())
 
-external unsafe_output : out_channel -> string -> int -> int -> unit
+external unsafe_output : out_channel -> bytes -> int -> int -> unit
                        = "caml_ml_output"
 
 external output_char : out_channel -> char -> unit = "caml_ml_output_char"
 
+let output_bytes oc s =
+  unsafe_output oc s 0 (bytes_length s)
+
 let output_string oc s =
-  unsafe_output oc s 0 (string_length s)
+  unsafe_output oc (bytes_unsafe_of_string s) 0 (string_length s)
 
 let output oc s ofs len =
-  if ofs < 0 || len < 0 || ofs > string_length s - len
+  if ofs < 0 || len < 0 || ofs > bytes_length s - len
   then invalid_arg "output"
   else unsafe_output oc s ofs len
 
+let output_substring oc s ofs len =
+  output oc (bytes_unsafe_of_string s) ofs len
+
 external output_byte : out_channel -> int -> unit = "caml_ml_output_char"
 external output_binary_int : out_channel -> int -> unit = "caml_ml_output_int"
 
@@ -332,11 +340,11 @@ let open_in_bin name =
 
 external input_char : in_channel -> char = "caml_ml_input_char"
 
-external unsafe_input : in_channel -> string -> int -> int -> int
+external unsafe_input : in_channel -> bytes -> int -> int -> int
                       = "caml_ml_input"
 
 let input ic s ofs len =
-  if ofs < 0 || len < 0 || ofs > string_length s - len
+  if ofs < 0 || len < 0 || ofs > bytes_length s - len
   then invalid_arg "input"
   else unsafe_input ic s ofs len
 
@@ -349,39 +357,44 @@ let rec unsafe_really_input ic s ofs len =
   end
 
 let really_input ic s ofs len =
-  if ofs < 0 || len < 0 || ofs > string_length s - len
+  if ofs < 0 || len < 0 || ofs > bytes_length s - len
   then invalid_arg "really_input"
   else unsafe_really_input ic s ofs len
 
+let really_input_string ic len =
+  let s = bytes_create len in
+  really_input ic s 0 len;
+  bytes_unsafe_to_string s
+
 external input_scan_line : in_channel -> int = "caml_ml_input_scan_line"
 
 let input_line chan =
   let rec build_result buf pos = function
     [] -> buf
   | hd :: tl ->
-      let len = string_length hd in
-      string_blit hd 0 buf (pos - len) len;
+      let len = bytes_length hd in
+      bytes_blit hd 0 buf (pos - len) len;
       build_result buf (pos - len) tl in
   let rec scan accu len =
     let n = input_scan_line chan in
     if n = 0 then begin                   (* n = 0: we are at EOF *)
       match accu with
         [] -> raise End_of_file
-      | _  -> build_result (string_create len) len accu
+      | _  -> build_result (bytes_create len) len accu
     end else if n > 0 then begin          (* n > 0: newline found in buffer *)
-      let res = string_create (n - 1) in
+      let res = bytes_create (n - 1) in
       ignore (unsafe_input chan res 0 (n - 1));
       ignore (input_char chan);           (* skip the newline *)
       match accu with
         [] -> res
       |  _ -> let len = len + n - 1 in
-              build_result (string_create len) len (res :: accu)
+              build_result (bytes_create len) len (res :: accu)
     end else begin                        (* n < 0: newline not found *)
-      let beg = string_create (-n) in
+      let beg = bytes_create (-n) in
       ignore(unsafe_input chan beg 0 (-n));
       scan (beg :: accu) (len - n)
     end
-  in scan [] 0
+  in bytes_unsafe_to_string (scan [] 0)
 
 external input_byte : in_channel -> int = "caml_ml_input_char"
 external input_binary_int : in_channel -> int = "caml_ml_input_int"
@@ -398,6 +411,7 @@ external set_binary_mode_in : in_channel -> bool -> unit
 
 let print_char c = output_char stdout c
 let print_string s = output_string stdout s
+let print_bytes s = output_bytes stdout s
 let print_int i = output_string stdout (string_of_int i)
 let print_float f = output_string stdout (string_of_float f)
 let print_endline s =
@@ -455,12 +469,9 @@ let (( ^^ ) :
     string_to_format (format_to_string fmt1 ^ "%," ^ format_to_string fmt2)
 ;;
 
-let string_of_format fmt =
-  let s = format_to_string fmt in
-  let l = string_length s in
-  let r = string_create l in
-  string_blit s 0 r 0 l;
-  r
+(* Have to return a copy for compatibility with unsafe-string mode *)
+(* String.copy is not available here, so use ^ to make a copy of the string *)
+let string_of_format fmt = format_to_string fmt ^ ""
 
 (* Miscellaneous *)
 
diff --git a/stdlib/pervasives.mli b/stdlib/pervasives.mli
index 1ee09984c7..3ec9c8c9ab 100644
--- a/stdlib/pervasives.mli
+++ b/stdlib/pervasives.mli
@@ -566,6 +566,9 @@ val print_char : char -> unit
 val print_string : string -> unit
 (** Print a string on standard output. *)
 
+val print_bytes : bytes -> unit
+(** Print a byte sequence on standard output. *)
+
 val print_int : int -> unit
 (** Print an integer, in decimal, on standard output. *)
 
@@ -597,8 +600,8 @@ val prerr_float : float -> unit
 (** Print a floating-point number, in decimal, on standard error. *)
 
 val prerr_endline : string -> unit
-(** Print a string, followed by a newline character on standard error
-   and flush standard error. *)
+(** Print a string, followed by a newline character on standard
+   error and flush standard error. *)
 
 val prerr_newline : unit -> unit
 (** Print a newline character on standard error, and flush
@@ -674,11 +677,18 @@ val output_char : out_channel -> char -> unit
 val output_string : out_channel -> string -> unit
 (** Write the string on the given output channel. *)
 
-val output : out_channel -> string -> int -> int -> unit
-(** [output oc buf pos len] writes [len] characters from string [buf],
+val output_bytes : out_channel -> bytes -> unit
+(** Write the byte sequence on the given output channel. *)
+
+val output : out_channel -> bytes -> int -> int -> unit
+(** [output oc buf pos len] writes [len] characters from byte sequence [buf],
    starting at offset [pos], to the given output channel [oc].
    Raise [Invalid_argument "output"] if [pos] and [len] do not
-   designate a valid substring of [buf]. *)
+   designate a valid range of [buf]. *)
+
+val output_substring : out_channel -> string -> int -> int -> unit
+(** Same as [output] but take a string as argument instead of
+   a byte sequence. *)
 
 val output_byte : out_channel -> int -> unit
 (** Write one 8-bit integer (as the single character with that code)
@@ -769,9 +779,9 @@ val input_line : in_channel -> string
    Raise [End_of_file] if the end of the file is reached
    at the beginning of line. *)
 
-val input : in_channel -> string -> int -> int -> int
+val input : in_channel -> bytes -> int -> int -> int
 (** [input ic buf pos len] reads up to [len] characters from
-   the given channel [ic], storing them in string [buf], starting at
+   the given channel [ic], storing them in byte sequence [buf], starting at
    character number [pos].
    It returns the actual number of characters read, between 0 and
    [len] (inclusive).
@@ -784,15 +794,21 @@ val input : in_channel -> string -> int -> int -> int
    if desired.  (See also {!Pervasives.really_input} for reading
    exactly [len] characters.)
    Exception [Invalid_argument "input"] is raised if [pos] and [len]
-   do not designate a valid substring of [buf]. *)
+   do not designate a valid range of [buf]. *)
 
-val really_input : in_channel -> string -> int -> int -> unit
+val really_input : in_channel -> bytes -> int -> int -> unit
 (** [really_input ic buf pos len] reads [len] characters from channel [ic],
-   storing them in string [buf], starting at character number [pos].
+   storing them in byte sequence [buf], starting at character number [pos].
    Raise [End_of_file] if the end of file is reached before [len]
    characters have been read.
    Raise [Invalid_argument "really_input"] if
-   [pos] and [len] do not designate a valid substring of [buf]. *)
+   [pos] and [len] do not designate a valid range of [buf]. *)
+
+val really_input_string : in_channel -> int -> string
+(** [really_input_string ic len] reads [len] characters from channel [ic]
+   and returns them in a new string.
+   Raise [End_of_file] if the end of file is reached before [len]
+   characters have been read. *)
 
 val input_byte : in_channel -> int
 (** Same as {!Pervasives.input_char}, but return the 8-bit integer representing
@@ -1016,6 +1032,6 @@ val at_exit : (unit -> unit) -> unit
 
 val valid_float_lexem : string -> string
 
-val unsafe_really_input : in_channel -> string -> int -> int -> unit
+val unsafe_really_input : in_channel -> bytes -> int -> int -> unit
 
 val do_at_exit : unit -> unit
diff --git a/stdlib/printf.ml b/stdlib/printf.ml
index 3801692047..54052e820d 100644
--- a/stdlib/printf.ml
+++ b/stdlib/printf.ml
@@ -100,11 +100,11 @@ let parse_string_conversion sfmt =
 let pad_string pad_char p neg s i len =
   if p = len && i = 0 then s else
   if p <= len then String.sub s i len else
-  let res = String.make p pad_char in
+  let res = Bytes.make p pad_char in
   if neg
   then String.blit s i res 0 len
   else String.blit s i res (p - len) len;
-  res
+  Bytes.unsafe_to_string res
 ;;
 
 (* Format a string given a %s format, e.g. %40s or %-20s.
@@ -152,8 +152,8 @@ let extract_format_int conv fmt start stop widths =
   let sfmt = extract_format fmt start stop widths in
   match conv with
   | 'n' | 'N' ->
-    sfmt.[String.length sfmt - 1] <- 'u';
-    sfmt
+    let len = String.length sfmt in
+    String.sub sfmt 0 (len - 1) ^ "u"
   | _ -> sfmt
 ;;
 
@@ -161,8 +161,8 @@ let extract_format_float conv fmt start stop widths =
   let sfmt = extract_format fmt start stop widths in
   match conv with
   | 'F' ->
-    sfmt.[String.length sfmt - 1] <- 'g';
-    sfmt
+    let len = String.length sfmt in
+    String.sub sfmt 0 (len - 1) ^ "g"
   | _ -> sfmt
 ;;
 
diff --git a/stdlib/scanf.ml b/stdlib/scanf.ml
index 8f694fd3a2..69837c4704 100644
--- a/stdlib/scanf.ml
+++ b/stdlib/scanf.ml
@@ -318,17 +318,17 @@ module Scanning : SCANNING = struct
 
   let from_ic scan_close_ic iname ic =
     let len = !file_buffer_size in
-    let buf = String.create len in
+    let buf = Bytes.create len in
     let i = ref 0 in
     let lim = ref 0 in
     let eof = ref false in
     let next () =
-      if !i < !lim then begin let c = buf.[!i] in incr i; c end else
+      if !i < !lim then begin let c = Bytes.get buf !i in incr i; c end else
       if !eof then raise End_of_file else begin
         lim := input ic buf 0 len;
         if !lim = 0 then begin eof := true; scan_close_ic ic end else begin
           i := 1;
-          buf.[0]
+          Bytes.get buf 0
         end
       end in
     create iname next
@@ -1061,14 +1061,14 @@ let get_bit_of_byte byte idx = (byte lsr idx) land 1;;
 let set_bit_of_range r c b =
   let idx = c land 0x7 in
   let ydx = c lsr 3 in
-  let byte = r.[ydx] in
-  r.[ydx] <- char_of_int (set_bit_of_byte (int_of_char byte) idx b)
+  let byte = Bytes.get r ydx in
+  Bytes.set r ydx (char_of_int (set_bit_of_byte (int_of_char byte) idx b))
 ;;
 
 let get_bit_of_range r c =
   let idx = c land 0x7 in
   let ydx = c lsr 3 in
-  let byte = r.[ydx] in
+  let byte = Bytes.get r ydx in
   get_bit_of_byte (int_of_char byte) idx
 ;;
 
@@ -1077,7 +1077,7 @@ let get_bit_of_range r c =
 (* Create a full or empty set of chars. *)
 let make_range bit =
   let c = char_of_int (if bit = 0 then 0 else 0xFF) in
-  String.make 32 c
+  Bytes.make 32 c
 ;;
 
 (* Test if a char belongs to a set of chars. *)
@@ -1566,9 +1566,3 @@ let format_from_string s fmt =
 let unescaped s =
   sscanf ("\"" ^ s ^ "\"") "%S%!" (fun x -> x)
 ;;
-
-(*
- Local Variables:
-  compile-command: "cd ..; make world"
-  End:
-*)
diff --git a/stdlib/stdLabels.ml b/stdlib/stdLabels.ml
index 35b25e0b71..60713ca0cd 100644
--- a/stdlib/stdLabels.ml
+++ b/stdlib/stdLabels.ml
@@ -18,3 +18,5 @@ module Array = ArrayLabels
 module List = ListLabels
 
 module String = StringLabels
+
+module Bytes = BytesLabels
diff --git a/stdlib/stdLabels.mli b/stdlib/stdLabels.mli
index 144936f170..090a43e282 100644
--- a/stdlib/stdLabels.mli
+++ b/stdlib/stdLabels.mli
@@ -17,9 +17,11 @@
    {!List} and {!String} modules.
 
    They only differ by their labels. Detailed interfaces can be found
-   in [arrayLabels.mli], [listLabels.mli] and [stringLabels.mli].
+   in [arrayLabels.mli], [bytesLabels.mli], [listLabels.mli]
+   and [stringLabels.mli].
 *)
 
 module Array = ArrayLabels
+module Bytes = BytesLabels
 module List = ListLabels
 module String = StringLabels
diff --git a/stdlib/stream.ml b/stdlib/stream.ml
index 753bce0056..076b6733e5 100644
--- a/stdlib/stream.ml
+++ b/stdlib/stream.ml
@@ -25,7 +25,7 @@ and 'a data =
   | Sbuffio of buffio
 and 'a gen = { mutable curr : 'a option option; func : int -> 'a option }
 and buffio =
-  { ic : in_channel; buff : string; mutable len : int; mutable ind : int }
+  { ic : in_channel; buff : bytes; mutable len : int; mutable ind : int }
 ;;
 exception Failure;;
 exception Error of string;;
@@ -37,7 +37,7 @@ let set_data (s : 'a t) (d : 'a data) =
 ;;
 
 let fill_buff b =
-  b.len <- input b.ic b.buff 0 (String.length b.buff); b.ind <- 0
+  b.len <- input b.ic b.buff 0 (Bytes.length b.buff); b.ind <- 0
 ;;
 
 let rec get_data count d = match d with
@@ -64,7 +64,7 @@ let rec get_data count d = match d with
  | Sbuffio b ->
      if b.ind >= b.len then fill_buff b;
      if b.len == 0 then Sempty else
-       let r = Obj.magic (String.unsafe_get b.buff b.ind) in
+       let r = Obj.magic (Bytes.unsafe_get b.buff b.ind) in
        (* Warning: anyone using g thinks that an item has been read *)
        b.ind <- succ b.ind; Scons(r, d)
  | Slazy f -> get_data count (Lazy.force f)
@@ -87,7 +87,7 @@ let rec peek s =
  | Sbuffio b ->
      if b.ind >= b.len then fill_buff b;
      if b.len == 0 then begin set_data s Sempty; None end
-     else Some (Obj.magic (String.unsafe_get b.buff b.ind))
+     else Some (Obj.magic (Bytes.unsafe_get b.buff b.ind))
 ;;
 
 let rec junk s =
@@ -161,7 +161,7 @@ let of_string s =
 
 let of_channel ic =
   {count = 0;
-   data = Sbuffio {ic = ic; buff = String.create 4096; len = 0; ind = 0}}
+   data = Sbuffio {ic = ic; buff = Bytes.create 4096; len = 0; ind = 0}}
 ;;
 
 (* Stream expressions builders *)
diff --git a/stdlib/string.ml b/stdlib/string.ml
index fda40b5279..064c3fdbeb 100644
--- a/stdlib/string.ml
+++ b/stdlib/string.ml
@@ -2,203 +2,82 @@
 (*                                                                     *)
 (*                                OCaml                                *)
 (*                                                                     *)
-(*            Xavier Leroy, projet Cristal, INRIA Rocquencourt         *)
+(*          Damien Doligez, projet Gallium, INRIA Rocquencourt         *)
 (*                                                                     *)
-(*  Copyright 1996 Institut National de Recherche en Informatique et   *)
+(*  Copyright 2014 Institut National de Recherche en Informatique et   *)
 (*  en Automatique.  All rights reserved.  This file is distributed    *)
 (*  under the terms of the GNU Library General Public License, with    *)
 (*  the special exception on linking described in file ../LICENSE.     *)
 (*                                                                     *)
 (***********************************************************************)
 
-(* String operations *)
+(* String operations, based on byte sequence operations *)
 
 external length : string -> int = "%string_length"
 external get : string -> int -> char = "%string_safe_get"
-external set : string -> int -> char -> unit = "%string_safe_set"
-external create : int -> string = "caml_create_string"
+external set : bytes -> int -> char -> unit = "%string_safe_set"
+external create : int -> bytes = "caml_create_string"
 external unsafe_get : string -> int -> char = "%string_unsafe_get"
-external unsafe_set : string -> int -> char -> unit = "%string_unsafe_set"
-external unsafe_blit : string -> int -> string -> int -> int -> unit
+external unsafe_set : bytes -> int -> char -> unit = "%string_unsafe_set"
+external unsafe_blit : string -> int ->  bytes -> int -> int -> unit
                      = "caml_blit_string" "noalloc"
-external unsafe_fill : string -> int -> int -> char -> unit
+external unsafe_fill : bytes -> int -> int -> char -> unit
                      = "caml_fill_string" "noalloc"
 
-let make n c =
-  let s = create n in
-  unsafe_fill s 0 n c;
-  s
+module B = Bytes
 
-let copy s =
-  let len = length s in
-  let r = create len in
-  unsafe_blit s 0 r 0 len;
-  r
+let make = (Obj.magic B.make : int -> char -> string)
+let copy = (Obj.magic B.copy : string -> string)
+let sub = (Obj.magic B.sub : string -> int -> int -> string)
+let fill = B.fill
+let blit =
+  (Obj.magic B.blit : string -> int -> bytes -> int -> int -> unit)
+let concat = (Obj.magic B.concat : string -> string list -> string)
+let iter = (Obj.magic B.iter : (char -> unit) -> string -> unit)
+let iteri = (Obj.magic B.iteri : (int -> char -> unit) -> string -> unit)
+let map = (Obj.magic B.map : (char -> char) -> string -> string)
 
-let sub s ofs len =
-  if ofs < 0 || len < 0 || ofs > length s - len
-  then invalid_arg "String.sub"
-  else begin
-    let r = create len in
-    unsafe_blit s ofs r 0 len;
-    r
-  end
-
-let fill s ofs len c =
-  if ofs < 0 || len < 0 || ofs > length s - len
-  then invalid_arg "String.fill"
-  else unsafe_fill s ofs len c
-
-let blit s1 ofs1 s2 ofs2 len =
-  if len < 0 || ofs1 < 0 || ofs1 > length s1 - len
-             || ofs2 < 0 || ofs2 > length s2 - len
-  then invalid_arg "String.blit"
-  else unsafe_blit s1 ofs1 s2 ofs2 len
-
-let iter f a =
-  for i = 0 to length a - 1 do f(unsafe_get a i) done
-
-let iteri f a =
-  for i = 0 to length a - 1 do f i (unsafe_get a i) done
-
-let concat sep l =
-  match l with
-    [] -> ""
-  | hd :: tl ->
-      let num = ref 0 and len = ref 0 in
-      List.iter (fun s -> incr num; len := !len + length s) l;
-      let r = create (!len + length sep * (!num - 1)) in
-      unsafe_blit hd 0 r 0 (length hd);
-      let pos = ref(length hd) in
-      List.iter
-        (fun s ->
-          unsafe_blit sep 0 r !pos (length sep);
-          pos := !pos + length sep;
-          unsafe_blit s 0 r !pos (length s);
-          pos := !pos + length s)
-        tl;
-      r
+(* Beware: we cannot use B.trim or B.escape because they always make a
+   copy, but String.mli spells out some cases where we are not allowed
+   to make a copy. *)
 
 external is_printable: char -> bool = "caml_is_printable"
-external char_code: char -> int = "%identity"
-external char_chr: int -> char = "%identity"
 
 let is_space = function
   | ' ' | '\012' | '\n' | '\r' | '\t' -> true
   | _ -> false
 
 let trim s =
-  let len = length s in
-  let i = ref 0 in
-  while !i < len && is_space (unsafe_get s !i) do
-    incr i
-  done;
-  let j = ref (len - 1) in
-  while !j >= !i && is_space (unsafe_get s !j) do
-    decr j
-  done;
-  if !i = 0 && !j = len - 1 then
-    s
-  else if !j >= !i then
-    sub s !i (!j - !i + 1)
-  else
-    ""
+  if s = "" then s
+  else if is_space (unsafe_get s 0) || is_space (unsafe_get s (length s - 1))
+    then B.unsafe_to_string (B.trim (B.unsafe_of_string s))
+  else s
 
 let escaped s =
-  let n = ref 0 in
-    for i = 0 to length s - 1 do
-      n := !n +
-        (match unsafe_get s i with
-         | '"' | '\\' | '\n' | '\t' | '\r' | '\b' -> 2
-         | c -> if is_printable c then 1 else 4)
-    done;
-    if !n = length s then s else begin
-      let s' = create !n in
-        n := 0;
-        for i = 0 to length s - 1 do
-          begin
-            match unsafe_get s i with
-            | ('"' | '\\') as c ->
-                unsafe_set s' !n '\\'; incr n; unsafe_set s' !n c
-            | '\n' ->
-                unsafe_set s' !n '\\'; incr n; unsafe_set s' !n 'n'
-            | '\t' ->
-                unsafe_set s' !n '\\'; incr n; unsafe_set s' !n 't'
-            | '\r' ->
-                unsafe_set s' !n '\\'; incr n; unsafe_set s' !n 'r'
-            | '\b' ->
-                unsafe_set s' !n '\\'; incr n; unsafe_set s' !n 'b'
-            | c ->
-                if is_printable c then
-                  unsafe_set s' !n c
-                else begin
-                  let a = char_code c in
-                  unsafe_set s' !n '\\';
-                  incr n;
-                  unsafe_set s' !n (char_chr (48 + a / 100));
-                  incr n;
-                  unsafe_set s' !n (char_chr (48 + (a / 10) mod 10));
-                  incr n;
-                  unsafe_set s' !n (char_chr (48 + a mod 10))
-                end
-          end;
-          incr n
-        done;
-        s'
-      end
-
-let map f s =
-  let l = length s in
-  if l = 0 then s else begin
-    let r = create l in
-    for i = 0 to l - 1 do unsafe_set r i (f(unsafe_get s i)) done;
-    r
-  end
-
-let uppercase s = map Char.uppercase s
-let lowercase s = map Char.lowercase s
-
-let apply1 f s =
-  if length s = 0 then s else begin
-    let r = copy s in
-    unsafe_set r 0 (f(unsafe_get s 0));
-    r
-  end
-
-let capitalize s = apply1 Char.uppercase s
-let uncapitalize s = apply1 Char.lowercase s
-
-let rec index_rec s lim i c =
-  if i >= lim then raise Not_found else
-  if unsafe_get s i = c then i else index_rec s lim (i + 1) c;;
-
-let index s c = index_rec s (length s) 0 c;;
-
-let index_from s i c =
-  let l = length s in
-  if i < 0 || i > l then invalid_arg "String.index_from" else
-  index_rec s l i c;;
-
-let rec rindex_rec s i c =
-  if i < 0 then raise Not_found else
-  if unsafe_get s i = c then i else rindex_rec s (i - 1) c;;
-
-let rindex s c = rindex_rec s (length s - 1) c;;
-
-let rindex_from s i c =
-  if i < -1 || i >= length s then invalid_arg "String.rindex_from" else
-  rindex_rec s i c;;
-
-let contains_from s i c =
-  let l = length s in
-  if i < 0 || i > l then invalid_arg "String.contains_from" else
-  try ignore (index_rec s l i c); true with Not_found -> false;;
-
-let contains s c = contains_from s 0 c;;
+  let rec needs_escape i =
+    if i >= length s then false else
+      match unsafe_get s i with
+      | '"' | '\\' | '\n' | '\t' | '\r' | '\b' -> true
+      | c when is_printable c -> needs_escape (i+1)
+      | _ -> true
+  in
+  if needs_escape 0 then
+    B.unsafe_to_string (B.escaped (B.unsafe_of_string s))
+  else
+    s
 
-let rcontains_from s i c =
-  if i < 0 || i >= length s then invalid_arg "String.rcontains_from" else
-  try ignore (rindex_rec s i c); true with Not_found -> false;;
+let index = (Obj.magic B.index : string -> char -> int)
+let rindex = (Obj.magic B.rindex : string -> char -> int)
+let index_from = (Obj.magic B.index_from : string -> int -> char -> int)
+let rindex_from = (Obj.magic B.rindex_from : string -> int -> char -> int)
+let contains = (Obj.magic B.contains : string -> char -> bool)
+let contains_from = (Obj.magic B.contains_from : string -> int -> char -> bool)
+let rcontains_from =
+  (Obj.magic B.rcontains_from : string -> int -> char -> bool)
+let uppercase = (Obj.magic B.uppercase : string -> string)
+let lowercase = (Obj.magic B.lowercase : string -> string)
+let capitalize = (Obj.magic B.capitalize : string -> string)
+let uncapitalize = (Obj.magic B.uncapitalize : string -> string)
 
 type t = string
 
diff --git a/stdlib/string.mli b/stdlib/string.mli
index 14f2c82dbb..3cbf63c1b4 100644
--- a/stdlib/string.mli
+++ b/stdlib/string.mli
@@ -13,41 +13,36 @@
 
 (** String operations.
 
-  Given a string [s] of length [l], we call character number in [s]
-  the index of a character in [s].  Indexes start at [0], and we will
-  call a character number valid in [s] if it falls within the range
-  [[0...l-1]]. A position is the point between two characters or at
-  the beginning or end of the string.  We call a position valid
-  in [s] if it falls within the range [[0...l]]. Note that character
-  number [n] is between positions [n] and [n+1].
+  A string is an immutable data structure that contains a
+  fixed-length sequence of (single-byte) characters. Each character
+  can be accessed in constant time through its index.
+
+  Given a string [s] of length [l], we can acces each of the [l]
+  characters of [s] via its index in the sequence. Indexes start at
+  [0], and we will call an index valid in [s] if it falls within the
+  range [[0...l-1]] (inclusive). A position is the point between two
+  characters or at the beginning or end of the string.  We call a
+  position valid in [s] if it falls within the range [[0...l]]
+  (inclusive). Note that the character at index [n] is between
+  positions [n] and [n+1].
 
   Two parameters [start] and [len] are said to designate a valid
   substring of [s] if [len >= 0] and [start] and [start+len] are
   valid positions in [s].
 
-  OCaml strings can be modified in place, for instance via the
-  {!String.set} and {!String.blit} functions described below.  This
-  possibility should be used rarely and with much care, however, since
-  both the OCaml compiler and most OCaml libraries share strings as if
-  they were immutable, rather than copying them.  In particular,
-  string literals are shared: a single copy of the string is created
-  at program loading time and returned by all evaluations of the
-  string literal.  Consider for example:
-
-  {[
-      # let f () = "foo";;
-      val f : unit -> string = <fun>
-      # (f ()).[0] <- 'b';;
-      - : unit = ()
-      # f ();;
-      - : string = "boo"
-  ]}
-
-  Likewise, many functions from the standard library can return string
-  literals or one of their string arguments.  Therefore, the returned strings
-  must not be modified directly.  If mutation is absolutely necessary,
-  it should be performed on a fresh copy of the string, as produced by
-  {!String.copy}.
+  OCaml strings used to be modifiable in place, for instance via the
+  {!String.set} and {!String.blit} functions described below. This
+  usage is deprecated and only possible when the compiler is put in
+  "unsafe-string" mode by giving the [-unsafe-string] command-line
+  option (which is currently the default for reasons of backward
+  compatibility). This is done by making the types [string] and
+  [bytes] (see module {!Bytes}) interchangeable so that functions
+  expecting byte sequences can also accept strings as arguments and
+  modify them.
+
+  All new code should avoid this feature and be compiled with the
+  [-safe-string] command-line option to enforce the separation between
+  the types [string] and [bytes].
 
  *)
 
@@ -55,30 +50,35 @@ external length : string -> int = "%string_length"
 (** Return the length (number of characters) of the given string. *)
 
 external get : string -> int -> char = "%string_safe_get"
-(** [String.get s n] returns character number [n] in string [s].
+(** [String.get s n] returns the character at index [n] in string [s].
    You can also write [s.[n]] instead of [String.get s n].
 
-   Raise [Invalid_argument] if [n] not a valid character number in [s]. *)
+   Raise [Invalid_argument] if [n] not a valid index in [s]. *)
 
 
-external set : string -> int -> char -> unit = "%string_safe_set"
-(** [String.set s n c] modifies string [s] in place,
-   replacing the character number [n] by [c].
+external set : bytes -> int -> char -> unit = "%string_safe_set"
+  [@@ocaml.deprecated]
+(** [String.set s n c] modifies byte sequence [s] in place,
+   replacing the byte at index [n] with [c].
    You can also write [s.[n] <- c] instead of [String.set s n c].
 
-   Raise [Invalid_argument] if [n] is not a valid character number in [s]. *)
+   Raise [Invalid_argument] if [n] is not a valid index in [s].
 
-external create : int -> string = "caml_create_string"
-(** [String.create n] returns a fresh string of length [n].
-   The string initially contains arbitrary characters.
+   @deprecated This is a deprecated alias of {!Bytes.set}. *)
 
-   Raise [Invalid_argument] if [n < 0] or [n > ]{!Sys.max_string_length}. *)
+external create : int -> bytes = "caml_create_string" [@@ocaml.deprecated]
+(** [String.create n] returns a fresh byte sequence of length [n].
+   The sequence is uninitialized and contains arbitrary bytes.
+
+   Raise [Invalid_argument] if [n < 0] or [n > ]{!Sys.max_string_length}.
+
+   @deprecated This is a deprecated alias of {!Bytes.create}. *)
 
 val make : int -> char -> string
 (** [String.make n c] returns a fresh string of length [n],
    filled with the character [c].
 
-   Raise [Invalid_argument] if [n < 0] or [n > ]{!Sys.max_string_length}.*)
+   Raise [Invalid_argument] if [n < 0] or [n > ]{!Sys.max_string_length}. *)
 
 val copy : string -> string
 (** Return a copy of the given string. *)
@@ -91,23 +91,23 @@ val sub : string -> int -> int -> string
    Raise [Invalid_argument] if [start] and [len] do not
    designate a valid substring of [s]. *)
 
-val fill : string -> int -> int -> char -> unit
-(** [String.fill s start len c] modifies string [s] in place,
-   replacing [len] characters by [c], starting at [start].
+val fill : bytes -> int -> int -> char -> unit [@@ocaml.deprecated]
+(** [String.fill s start len c] modifies byte sequence [s] in place,
+   replacing [len] bytes with [c], starting at [start].
 
    Raise [Invalid_argument] if [start] and [len] do not
-   designate a valid substring of [s]. *)
+   designate a valid range of [s].
 
-val blit : string -> int -> string -> int -> int -> unit
+   @deprecated This is a deprecated alias of {!Bytes.fill}. *)
+
+val blit : string -> int -> bytes -> int -> int -> unit
 (** [String.blit src srcoff dst dstoff len] copies [len] characters
-   from string [src], starting at character number [srcoff], to
-   string [dst], starting at character number [dstoff]. It works
-   correctly even if [src] and [dst] are the same string,
-   and the source and destination intervals overlap.
+   (bytes) from the string [src], starting at index [srcoff], to byte
+   sequence [dst], starting at index [dstoff].
 
    Raise [Invalid_argument] if [srcoff] and [len] do not
    designate a valid substring of [src], or if [dstoff] and [len]
-   do not designate a valid substring of [dst]. *)
+   do not designate a valid range of [dst]. *)
 
 val concat : string -> string list -> string
 (** [String.concat sep sl] concatenates the list of strings [sl],
@@ -122,8 +122,7 @@ val iteri : (int -> char -> unit) -> string -> unit
 (** Same as {!String.iter}, but the
    function is applied to the index of the element as first argument
    (counting from 0), and the character itself as second argument.
-   @since 4.00.0
-*)
+   @since 4.00.0 *)
 
 val map : (char -> char) -> string -> string
 (** [String.map f s] applies function [f] in turn to all
@@ -147,19 +146,19 @@ val escaped : string -> string
    not a copy. Its inverse function is Scanf.unescaped. *)
 
 val index : string -> char -> int
-(** [String.index s c] returns the character number of the first
+(** [String.index s c] returns the index of the first
    occurrence of character [c] in string [s].
 
    Raise [Not_found] if [c] does not occur in [s]. *)
 
 val rindex : string -> char -> int
-(** [String.rindex s c] returns the character number of the last
+(** [String.rindex s c] returns the index of the last
    occurrence of character [c] in string [s].
 
    Raise [Not_found] if [c] does not occur in [s]. *)
 
 val index_from : string -> int -> char -> int
-(** [String.index_from s i c] returns the character number of the
+(** [String.index_from s i c] returns the index of the
    first occurrence of character [c] in string [s] after position [i].
    [String.index s c] is equivalent to [String.index_from s 0 c].
 
@@ -167,7 +166,7 @@ val index_from : string -> int -> char -> int
    Raise [Not_found] if [c] does not occur in [s] after position [i]. *)
 
 val rindex_from : string -> int -> char -> int
-(** [String.rindex_from s i c] returns the character number of the
+(** [String.rindex_from s i c] returns the index of the
    last occurrence of character [c] in string [s] before position [i+1].
    [String.rindex s c] is equivalent to
    [String.rindex_from s (String.length s - 1) c].
@@ -224,8 +223,11 @@ val compare: t -> t -> int
 (* The following is for system use only. Do not call directly. *)
 
 external unsafe_get : string -> int -> char = "%string_unsafe_get"
-external unsafe_set : string -> int -> char -> unit = "%string_unsafe_set"
+external unsafe_set : bytes -> int -> char -> unit = "%string_unsafe_set"
+  [@@ocaml.deprecated]
 external unsafe_blit :
-  string -> int -> string -> int -> int -> unit = "caml_blit_string" "noalloc"
+  string -> int -> bytes -> int -> int -> unit
+  = "caml_blit_string" "noalloc"
 external unsafe_fill :
-  string -> int -> int -> char -> unit = "caml_fill_string" "noalloc"
+  bytes -> int -> int -> char -> unit = "caml_fill_string" "noalloc"
+  [@@ocaml.deprecated]
diff --git a/stdlib/stringLabels.mli b/stdlib/stringLabels.mli
index 8e2e6d3798..4ae8a72e1a 100644
--- a/stdlib/stringLabels.mli
+++ b/stdlib/stringLabels.mli
@@ -17,61 +17,65 @@ external length : string -> int = "%string_length"
 (** Return the length (number of characters) of the given string. *)
 
 external get : string -> int -> char = "%string_safe_get"
-(** [String.get s n] returns character number [n] in string [s].
-   The first character is character number 0.
-   The last character is character number [String.length s - 1].
+(** [String.get s n] returns the character at index [n] in string [s].
    You can also write [s.[n]] instead of [String.get s n].
 
-   Raise [Invalid_argument "index out of bounds"]
-   if [n] is outside the range 0 to [(String.length s - 1)]. *)
+   Raise [Invalid_argument] if [n] not a valid index in [s]. *)
 
-
-external set : string -> int -> char -> unit = "%string_safe_set"
-(** [String.set s n c] modifies string [s] in place,
-   replacing the character number [n] by [c].
+external set : bytes -> int -> char -> unit = "%string_safe_set"
+  [@@ocaml.deprecated]
+(** [String.set s n c] modifies byte sequence [s] in place,
+   replacing the byte at index [n] with [c].
    You can also write [s.[n] <- c] instead of [String.set s n c].
-   Raise [Invalid_argument "index out of bounds"]
-   if [n] is outside the range 0 to [(String.length s - 1)]. *)
 
-external create : int -> string = "caml_create_string"
-(** [String.create n] returns a fresh string of length [n].
-   The string initially contains arbitrary characters.
-   Raise [Invalid_argument] if [n < 0] or [n > Sys.max_string_length].
-*)
+   Raise [Invalid_argument] if [n] is not a valid index in [s].
+
+   @deprecated This is a deprecated alias of {!Bytes.set}. *)
+
+external create : int -> bytes = "caml_create_string" [@@ocaml.deprecated]
+(** [String.create n] returns a fresh byte sequence of length [n].
+   The sequence is uninitialized and contains arbitrary bytes.
+
+   Raise [Invalid_argument] if [n < 0] or [n > ]{!Sys.max_string_length}.
+
+   @deprecated This is a deprecated alias of {!Bytes.create}. *)
 
 val make : int -> char -> string
 (** [String.make n c] returns a fresh string of length [n],
    filled with the character [c].
-   Raise [Invalid_argument] if [n < 0] or [n > ]{!Sys.max_string_length}.*)
+
+   Raise [Invalid_argument] if [n < 0] or [n > ]{!Sys.max_string_length}. *)
 
 val copy : string -> string
 (** Return a copy of the given string. *)
 
 val sub : string -> pos:int -> len:int -> string
 (** [String.sub s start len] returns a fresh string of length [len],
-   containing the characters number [start] to [start + len - 1]
-   of string [s].
-   Raise [Invalid_argument] if [start] and [len] do not
-   designate a valid substring of [s]; that is, if [start < 0],
-   or [len < 0], or [start + len > ]{!StringLabels.length}[ s]. *)
+   containing the substring of [s] that starts at position [start] and
+   has length [len].
 
-val fill : string -> pos:int -> len:int -> char -> unit
-(** [String.fill s start len c] modifies string [s] in place,
-   replacing the characters number [start] to [start + len - 1]
-   by [c].
    Raise [Invalid_argument] if [start] and [len] do not
    designate a valid substring of [s]. *)
 
+val fill : bytes -> pos:int -> len:int -> char -> unit [@@ocaml.deprecated]
+(** [String.fill s start len c] modifies byte sequence [s] in place,
+   replacing [len] bytes by [c], starting at [start].
+
+   Raise [Invalid_argument] if [start] and [len] do not
+   designate a valid substring of [s].
+
+   @deprecated This is a deprecated alias of {!Bytes.fill}. *)
+
 val blit :
-  src:string -> src_pos:int -> dst:string -> dst_pos:int -> len:int -> unit
-(** [String.blit src srcoff dst dstoff len] copies [len] characters
-   from string [src], starting at character number [srcoff], to
-   string [dst], starting at character number [dstoff]. It works
-   correctly even if [src] and [dst] are the same string,
-   and the source and destination chunks overlap.
+  src:string -> src_pos:int -> dst:bytes -> dst_pos:int -> len:int
+  -> unit
+(** [String.blit src srcoff dst dstoff len] copies [len] bytes
+   from the string [src], starting at index [srcoff],
+   to byte sequence [dst], starting at character number [dstoff].
+
    Raise [Invalid_argument] if [srcoff] and [len] do not
-   designate a valid substring of [src], or if [dstoff] and [len]
-   do not designate a valid substring of [dst]. *)
+   designate a valid range of [src], or if [dstoff] and [len]
+   do not designate a valid range of [dst]. *)
 
 val concat : sep:string -> string list -> string
 (** [String.concat sep sl] concatenates the list of strings [sl],
@@ -86,8 +90,7 @@ val iteri : f:(int -> char -> unit) -> string -> unit
 (** Same as {!String.iter}, but the
    function is applied to the index of the element as first argument
    (counting from 0), and the character itself as second argument.
-   @since 4.00.0
-*)
+   @since 4.00.0 *)
 
 val map : f:(char -> char) -> string -> string
 (** [String.map f s] applies function [f] in turn to all
@@ -96,10 +99,11 @@ val map : f:(char -> char) -> string -> string
    @since 4.00.0 *)
 
 val trim : string -> string
-(** Return a copy of the argument, without leading and trailing whitespace.
-   The characters regarded as whitespace are: [' '], ['\012'], ['\n'],
-   ['\r'], and ['\t'].  If there is no whitespace character in the argument,
-   return the original string itself, not a copy.
+(** Return a copy of the argument, without leading and trailing
+   whitespace.  The characters regarded as whitespace are: [' '],
+   ['\012'], ['\n'], ['\r'], and ['\t'].  If there is no leading nor
+   trailing whitespace character in the argument, return the original
+   string itself, not a copy.
    @since 4.00.0 *)
 
 val escaped : string -> string
@@ -107,28 +111,36 @@ val escaped : string -> string
    represented by escape sequences, following the lexical
    conventions of OCaml.  If there is no special
    character in the argument, return the original string itself,
-   not a copy. *)
+   not a copy. Its inverse function is Scanf.unescaped. *)
 
 val index : string -> char -> int
-(** [String.index s c] returns the position of the leftmost
+(** [String.index s c] returns the index of the first
    occurrence of character [c] in string [s].
+
    Raise [Not_found] if [c] does not occur in [s]. *)
 
 val rindex : string -> char -> int
-(** [String.rindex s c] returns the position of the rightmost
+(** [String.rindex s c] returns the index of the last
    occurrence of character [c] in string [s].
+
    Raise [Not_found] if [c] does not occur in [s]. *)
 
 val index_from : string -> int -> char -> int
-(** Same as {!StringLabels.index}, but start
-   searching at the character position given as second argument.
-   [String.index s c] is equivalent to [String.index_from s 0 c].*)
+(** [String.index_from s i c] returns the index of the
+   first occurrence of character [c] in string [s] after position [i].
+   [String.index s c] is equivalent to [String.index_from s 0 c].
+
+   Raise [Invalid_argument] if [i] is not a valid position in [s].
+   Raise [Not_found] if [c] does not occur in [s] after position [i]. *)
 
 val rindex_from : string -> int -> char -> int
-(** Same as {!StringLabels.rindex}, but start
-   searching at the character position given as second argument.
+(** [String.rindex_from s i c] returns the index of the
+   last occurrence of character [c] in string [s] before position [i+1].
    [String.rindex s c] is equivalent to
-   [String.rindex_from s (String.length s - 1) c]. *)
+   [String.rindex_from s (String.length s - 1) c].
+
+   Raise [Invalid_argument] if [i+1] is not a valid position in [s].
+   Raise [Not_found] if [c] does not occur in [s] before position [i+1]. *)
 
 val contains : string -> char -> bool
 (** [String.contains s c] tests if character [c]
@@ -136,15 +148,18 @@ val contains : string -> char -> bool
 
 val contains_from : string -> int -> char -> bool
 (** [String.contains_from s start c] tests if character [c]
-   appears in the substring of [s] starting from [start] to the end
-   of [s].
-   Raise [Invalid_argument] if [start] is not a valid index of [s]. *)
+   appears in [s] after position [start].
+   [String.contains s c] is equivalent to
+   [String.contains_from s 0 c].
+
+   Raise [Invalid_argument] if [start] is not a valid position in [s]. *)
 
 val rcontains_from : string -> int -> char -> bool
 (** [String.rcontains_from s stop c] tests if character [c]
-   appears in the substring of [s] starting from the beginning
-   of [s] to index [stop].
-   Raise [Invalid_argument] if [stop] is not a valid index of [s]. *)
+   appears in [s] before position [stop+1].
+
+   Raise [Invalid_argument] if [stop < 0] or [stop+1] is not a valid
+   position in [s]. *)
 
 val uppercase : string -> string
 (** Return a copy of the argument, with all lowercase letters
@@ -176,9 +191,11 @@ val compare: t -> t -> int
 (* The following is for system use only. Do not call directly. *)
 
 external unsafe_get : string -> int -> char = "%string_unsafe_get"
-external unsafe_set : string -> int -> char -> unit = "%string_unsafe_set"
+external unsafe_set : bytes -> int -> char -> unit = "%string_unsafe_set"
+  [@@ocaml.deprecated]
 external unsafe_blit :
-  src:string -> src_pos:int -> dst:string -> dst_pos:int -> len:int ->
+  src:string -> src_pos:int -> dst:bytes -> dst_pos:int -> len:int ->
     unit = "caml_blit_string" "noalloc"
 external unsafe_fill :
-  string -> pos:int -> len:int -> char -> unit = "caml_fill_string" "noalloc"
+  bytes -> pos:int -> len:int -> char -> unit = "caml_fill_string" "noalloc"
+  [@@ocaml.deprecated]
diff --git a/stdlib/sys.mli b/stdlib/sys.mli
index 944b1090f6..0f3b131ada 100644
--- a/stdlib/sys.mli
+++ b/stdlib/sys.mli
@@ -99,7 +99,7 @@ val big_endian : bool
     @since 4.00.0 *)
 
 val max_string_length : int
-(** Maximum length of a string. *)
+(** Maximum length of strings and byte sequences. *)
 
 val max_array_length : int
 (** Maximum length of a normal array.  The maximum length of a float
diff --git a/testsuite/tests/asmcomp/lexcmm.mll b/testsuite/tests/asmcomp/lexcmm.mll
index e9efdb60ff..4c262b1122 100644
--- a/testsuite/tests/asmcomp/lexcmm.mll
+++ b/testsuite/tests/asmcomp/lexcmm.mll
@@ -81,7 +81,7 @@ let keyword_table =
 
 (* To buffer string literals *)
 
-let initial_string_buffer = String.create 256
+let initial_string_buffer = Bytes.create 256
 let string_buff = ref initial_string_buffer
 let string_index = ref 0
 
@@ -90,16 +90,16 @@ let reset_string_buffer () =
   string_index := 0
 
 let store_string_char c =
-  if !string_index >= String.length (!string_buff) then begin
-    let new_buff = String.create (String.length (!string_buff) * 2) in
-      String.blit (!string_buff) 0 new_buff 0 (String.length (!string_buff));
-      string_buff := new_buff
+  if !string_index >= Bytes.length (!string_buff) then begin
+    let new_buff = Bytes.create (Bytes.length (!string_buff) * 2) in
+    Bytes.blit (!string_buff) 0 new_buff 0 (Bytes.length (!string_buff));
+    string_buff := new_buff
   end;
-  String.unsafe_set (!string_buff) (!string_index) c;
+  Bytes.unsafe_set (!string_buff) (!string_index) c;
   incr string_index
 
 let get_stored_string () =
-  let s = String.sub (!string_buff) 0 (!string_index) in
+  let s = Bytes.sub_string (!string_buff) 0 (!string_index) in
   string_buff := initial_string_buffer;
   s
 
diff --git a/testsuite/tests/basic-io-2/io.ml b/testsuite/tests/basic-io-2/io.ml
index 14e458cdde..8c71206a83 100644
--- a/testsuite/tests/basic-io-2/io.ml
+++ b/testsuite/tests/basic-io-2/io.ml
@@ -25,7 +25,7 @@ let test msg funct f1 f2 =
 let copy_file sz infile ofile =
   let ic = open_in_bin infile in
   let oc = open_out_bin ofile in
-  let buffer = String.create sz in
+  let buffer = Bytes.create sz in
   let rec copy () =
     let n = input ic buffer 0 sz in
     if n = 0 then () else begin
@@ -41,7 +41,7 @@ let copy_file sz infile ofile =
 let copy_random sz infile ofile =
   let ic = open_in_bin infile in
   let oc = open_out_bin ofile in
-  let buffer = String.create sz in
+  let buffer = Bytes.create sz in
   let rec copy () =
     let s = 1 + Random.int sz in
     let n = input ic buffer 0 s in
@@ -72,7 +72,7 @@ let copy_seek chunksize infile ofile =
   let ic = open_in_bin infile in
   let oc = open_out_bin ofile in
   let size = in_channel_length ic in
-  let buffer = String.create chunksize in
+  let buffer = Bytes.create chunksize in
   for i = (size - 1) / chunksize downto 0 do
     seek_in ic (i * chunksize);
     seek_out oc (i * chunksize);
diff --git a/testsuite/tests/embedded/cmcaml.ml b/testsuite/tests/embedded/cmcaml.ml
index 121cec36fe..b3e9b7e29d 100644
--- a/testsuite/tests/embedded/cmcaml.ml
+++ b/testsuite/tests/embedded/cmcaml.ml
@@ -18,7 +18,7 @@ let rec fib n =
 let format_result n =
   let r = "Result = " ^ string_of_int n in
   (* Allocate gratuitously to test GC *)
-  for i = 1 to 1500 do ignore (String.create 256) done;
+  for i = 1 to 1500 do ignore (Bytes.create 256) done;
   r
 
 (* Registration *)
diff --git a/testsuite/tests/lib-marshal/intext.ml b/testsuite/tests/lib-marshal/intext.ml
index 06f169e0bb..27ffd64d24 100644
--- a/testsuite/tests/lib-marshal/intext.ml
+++ b/testsuite/tests/lib-marshal/intext.ml
@@ -249,77 +249,77 @@ let marshal_to_buffer s start len v flags =
 ;;
 
 let test_buffer () =
-  let s = String.create 512 in
+  let s = Bytes.create 512 in
   marshal_to_buffer s 0 512 1 [];
-  test 201 (Marshal.from_string s 0 = 1);
+  test 201 (Marshal.from_bytes s 0 = 1);
   marshal_to_buffer s 0 512 (-1) [];
-  test 202 (Marshal.from_string s 0 = (-1));
+  test 202 (Marshal.from_bytes s 0 = (-1));
   marshal_to_buffer s 0 512 258 [];
-  test 203 (Marshal.from_string s 0 = 258);
+  test 203 (Marshal.from_bytes s 0 = 258);
   marshal_to_buffer s 0 512 20000 [];
-  test 204 (Marshal.from_string s 0 = 20000);
+  test 204 (Marshal.from_bytes s 0 = 20000);
   marshal_to_buffer s 0 512 0x12345678 [];
-  test 205 (Marshal.from_string s 0 = 0x12345678);
+  test 205 (Marshal.from_bytes s 0 = 0x12345678);
   marshal_to_buffer s 0 512 bigint [];
-  test 206 (Marshal.from_string s 0 = bigint);
+  test 206 (Marshal.from_bytes s 0 = bigint);
   marshal_to_buffer s 0 512 "foobargeebuz" [];
-  test 207 (Marshal.from_string s 0 = "foobargeebuz");
+  test 207 (Marshal.from_bytes s 0 = "foobargeebuz");
   marshal_to_buffer s 0 512 longstring [];
-  test 208 (Marshal.from_string s 0 = longstring);
+  test 208 (Marshal.from_bytes s 0 = longstring);
   test 209
     (try marshal_to_buffer s 0 512 verylongstring []; false
      with Failure "Marshal.to_buffer: buffer overflow" -> true);
   marshal_to_buffer s 0 512 3.141592654 [];
-  test 210 (Marshal.from_string s 0 = 3.141592654);
+  test 210 (Marshal.from_bytes s 0 = 3.141592654);
   marshal_to_buffer s 0 512 () [];
-  test 211 (Marshal.from_string s 0 = ());
+  test 211 (Marshal.from_bytes s 0 = ());
   marshal_to_buffer s 0 512 A [];
-  test 212 (match Marshal.from_string s 0 with
+  test 212 (match Marshal.from_bytes s 0 with
     A -> true
   | _ -> false);
   marshal_to_buffer s 0 512 (B 1) [];
-  test 213 (match Marshal.from_string s 0 with
+  test 213 (match Marshal.from_bytes s 0 with
     (B 1) -> true
   | _ -> false);
   marshal_to_buffer s 0 512 (C 2.718) [];
-  test 214 (match Marshal.from_string s 0 with
+  test 214 (match Marshal.from_bytes s 0 with
     (C f) -> f = 2.718
   | _ -> false);
   marshal_to_buffer s 0 512 (D "hello, world!") [];
-  test 215 (match Marshal.from_string s 0 with
+  test 215 (match Marshal.from_bytes s 0 with
     (D "hello, world!") -> true
   | _ -> false);
   marshal_to_buffer s 0 512 (E 'l') [];
-  test 216 (match Marshal.from_string s 0 with
+  test 216 (match Marshal.from_bytes s 0 with
     (E 'l') -> true
   | _ -> false);
   marshal_to_buffer s 0 512 (F(B 1)) [];
-  test 217 (match Marshal.from_string s 0 with
+  test 217 (match Marshal.from_bytes s 0 with
     (F(B 1)) -> true
   | _ -> false);
   marshal_to_buffer s 0 512 (G(A, G(B 2, G(C 3.14, G(D "glop", E 'e'))))) [];
-  test 218 (match Marshal.from_string s 0 with
+  test 218 (match Marshal.from_bytes s 0 with
     (G(A, G(B 2, G(C 3.14, G(D "glop", E 'e'))))) -> true
   | _ -> false);
   marshal_to_buffer s 0 512 (H(1, A)) [];
-  test 219 (match Marshal.from_string s 0 with
+  test 219 (match Marshal.from_bytes s 0 with
     (H(1, A)) -> true
   | _ -> false);
   marshal_to_buffer s 0 512 (I(B 2, 1e-6)) [];
-  test 220 (match Marshal.from_string s 0 with
+  test 220 (match Marshal.from_bytes s 0 with
     (I(B 2, 1e-6)) -> true
   | _ -> false);
   let x = D "sharing" in
   let y = G(x, x) in
   let z = G(y, G(x, y)) in
   marshal_to_buffer s 0 512 z [];
-  test 221 (match Marshal.from_string s 0 with
+  test 221 (match Marshal.from_bytes s 0 with
     G((G((D "sharing" as t1), t2) as t3), G(t4, t5)) ->
       t1 == t2 && t3 == t5 && t4 == t1
   | _ -> false);
   marshal_to_buffer s 0 512 [|1;2;3;4;5;6;7;8;9;10;11;12;13;14;15;16|] [];
   test 222
-       (Marshal.from_string s 0 = [|1;2;3;4;5;6;7;8;9;10;11;12;13;14;15;16|]);
+       (Marshal.from_bytes s 0 = [|1;2;3;4;5;6;7;8;9;10;11;12;13;14;15;16|]);
   let rec big n = if n <= 0 then A else H(n, big(n-1)) in
   test 223
     (try marshal_to_buffer s 0 512 (big 1000) []; false
diff --git a/testsuite/tests/regression/pr5757/pr5757.ml b/testsuite/tests/regression/pr5757/pr5757.ml
index 5395840c3b..3a40bb51f9 100644
--- a/testsuite/tests/regression/pr5757/pr5757.ml
+++ b/testsuite/tests/regression/pr5757/pr5757.ml
@@ -12,6 +12,6 @@
 
 Random.init 3;;
 for i = 0 to 100_000 do
-  ignore (String.create (Random.int 1_000_000))
+  ignore (Bytes.create (Random.int 1_000_000))
 done;;
 Printf.printf "hello world\n";;
diff --git a/tools/.depend b/tools/.depend
index a058ee37f3..ea66ede860 100644
--- a/tools/.depend
+++ b/tools/.depend
@@ -28,15 +28,13 @@ depend.cmx : ../parsing/parsetree.cmi ../utils/misc.cmx \
     ../parsing/longident.cmx ../parsing/location.cmx ../parsing/asttypes.cmi \
     depend.cmi
 dumpobj.cmo : ../utils/tbl.cmi opnames.cmo ../bytecomp/opcodes.cmo \
-    ../utils/misc.cmi ../parsing/location.cmi ../bytecomp/lambda.cmi \
-    ../bytecomp/instruct.cmi ../typing/ident.cmi ../utils/config.cmi \
-    ../bytecomp/cmo_format.cmi ../bytecomp/bytesections.cmi \
-    ../parsing/asttypes.cmi
+    ../parsing/location.cmi ../bytecomp/lambda.cmi ../bytecomp/instruct.cmi \
+    ../typing/ident.cmi ../utils/config.cmi ../bytecomp/cmo_format.cmi \
+    ../bytecomp/bytesections.cmi ../parsing/asttypes.cmi
 dumpobj.cmx : ../utils/tbl.cmx opnames.cmx ../bytecomp/opcodes.cmx \
-    ../utils/misc.cmx ../parsing/location.cmx ../bytecomp/lambda.cmx \
-    ../bytecomp/instruct.cmx ../typing/ident.cmx ../utils/config.cmx \
-    ../bytecomp/cmo_format.cmi ../bytecomp/bytesections.cmx \
-    ../parsing/asttypes.cmi
+    ../parsing/location.cmx ../bytecomp/lambda.cmx ../bytecomp/instruct.cmx \
+    ../typing/ident.cmx ../utils/config.cmx ../bytecomp/cmo_format.cmi \
+    ../bytecomp/bytesections.cmx ../parsing/asttypes.cmi
 eqparsetree.cmo : ../parsing/parsetree.cmi ../parsing/longident.cmi \
     ../parsing/location.cmi ../parsing/asttypes.cmi
 eqparsetree.cmx : ../parsing/parsetree.cmi ../parsing/longident.cmx \
diff --git a/tools/Makefile.shared b/tools/Makefile.shared
index 6b33a5b047..8fd3c9435e 100644
--- a/tools/Makefile.shared
+++ b/tools/Makefile.shared
@@ -13,12 +13,12 @@
 include ../config/Makefile
 
 CAMLRUN=../boot/ocamlrun
-CAMLC=$(CAMLRUN) ../boot/ocamlc -strict-sequence -nostdlib -I ../boot
+CAMLC=$(CAMLRUN) ../boot/ocamlc -nostdlib -I ../boot
 CAMLOPT=$(CAMLRUN) ../ocamlopt -nostdlib -I ../stdlib
 CAMLLEX=$(CAMLRUN) ../boot/ocamllex
 INCLUDES=-I ../utils -I ../parsing -I ../typing -I ../bytecomp -I ../asmcomp \
 	 -I ../driver -I ../toplevel
-COMPFLAGS= -w +32..39 -warn-error A $(INCLUDES)
+COMPFLAGS= -strict-sequence -w +32..39 -warn-error A -safe-string $(INCLUDES)
 LINKFLAGS=$(INCLUDES)
 
 all: ocamldep ocamlprof ocamlcp ocamloptp ocamlmktop ocamlmklib dumpobj \
diff --git a/tools/dumpobj.ml b/tools/dumpobj.ml
index f1255e9cd2..37bafa3afc 100644
--- a/tools/dumpobj.ml
+++ b/tools/dumpobj.ml
@@ -482,7 +482,7 @@ let print_reloc (info, pos) =
 (* Print a .cmo file *)
 
 let dump_obj filename ic =
-  let buffer = Misc.input_bytes ic (String.length cmo_magic_number) in
+  let buffer = really_input_string ic (String.length cmo_magic_number) in
   if buffer <> cmo_magic_number then begin
     prerr_endline "Not an object file"; exit 2
   end;
@@ -502,7 +502,7 @@ let dump_obj filename ic =
 (* Read the primitive table from an executable *)
 
 let read_primitive_table ic len =
-  let p = Misc.input_bytes ic len in
+  let p = really_input_string ic len in
   let rec split beg cur =
     if cur >= len then []
     else if p.[cur] = '\000' then
diff --git a/tools/objinfo.ml b/tools/objinfo.ml
index 6f3ec75665..0eb33882a0 100644
--- a/tools/objinfo.ml
+++ b/tools/objinfo.ml
@@ -31,7 +31,7 @@ let input_stringlist ic len =
       else acc
     in fold 0 0 []
   in
-  let sect = Misc.input_bytes ic len in
+  let sect = really_input_string ic len in
   get_string_list sect len
 
 let print_name_crc (name, crc) =
@@ -189,7 +189,7 @@ let dump_obj filename =
   printf "File %s\n" filename;
   let ic = open_in_bin filename in
   let len_magic_number = String.length cmo_magic_number in
-  let magic_number = Misc.input_bytes ic len_magic_number in
+  let magic_number = really_input_string ic len_magic_number in
   if magic_number = cmo_magic_number then begin
     let cu_pos = input_binary_int ic in
     seek_in ic cu_pos;
@@ -219,7 +219,7 @@ let dump_obj filename =
   end else begin
     let pos_trailer = in_channel_length ic - len_magic_number in
     let _ = seek_in ic pos_trailer in
-    let _ = really_input ic magic_number 0 len_magic_number in
+    let magic_number = really_input_string ic len_magic_number in
     if magic_number = Config.exec_magic_number then begin
       dump_byte ic;
       close_in ic
diff --git a/tools/ocamlcp.ml b/tools/ocamlcp.ml
index bca5ae63c5..1bc78ee870 100644
--- a/tools/ocamlcp.ml
+++ b/tools/ocamlcp.ml
@@ -77,12 +77,14 @@ module Options = Main_args.Make_bytecomp_options (struct
   let _principal = option "-principal"
   let _rectypes = option "-rectypes"
   let _runtime_variant s = option_with_arg "-runtime-variant" s
+  let _safe_string = option "-safe-string"
   let _short_paths = option "-short-paths"
   let _strict_sequence = option "-strict-sequence"
   let _trans_mod = option "-trans-mod"
   let _thread () = option "-thread" ()
   let _vmthread () = option "-vmthread" ()
   let _unsafe = option "-unsafe"
+  let _unsafe_string = option "-unsafe-string"
   let _use_prims s = option_with_arg "-use-prims" s
   let _use_runtime s = option_with_arg "-use-runtime" s
   let _v = option "-v"
diff --git a/tools/ocamldep.ml b/tools/ocamldep.ml
index 735a5f97b5..ea09c08036 100644
--- a/tools/ocamldep.ml
+++ b/tools/ocamldep.ml
@@ -35,11 +35,7 @@ let files = ref []
 
 let fix_slash s =
   if Sys.os_type = "Unix" then s else begin
-    let r = String.copy s in
-    for i = 0 to String.length r - 1 do
-      if r.[i] = '\\' then r.[i] <- '/'
-    done;
-    r
+    String.map (function '\\' -> '/' | c -> c) s
   end
 
 (* Since we reinitialize load_path after reading OCAMLCOMP,
@@ -160,20 +156,20 @@ let print_filename s =
       else count n (i+1)
     in
     let spaces = count 0 0 in
-    let result = String.create (String.length s + spaces) in
+    let result = Bytes.create (String.length s + spaces) in
     let rec loop i j =
       if i >= String.length s then ()
       else if s.[i] = ' ' then begin
-        result.[j] <- '\\';
-        result.[j+1] <- ' ';
+        Bytes.set result j '\\';
+        Bytes.set result (j+1) ' ';
         loop (i+1) (j+2);
       end else begin
-        result.[j] <- s.[i];
+        Bytes.set result j s.[i];
         loop (i+1) (j+1);
       end
     in
     loop 0 0;
-    print_string result;
+    print_bytes result;
   end
 ;;
 
@@ -324,8 +320,9 @@ let sort_files_by_dependencies files =
 
 (* Init Hashtbl with all defined modules *)
   let files = List.map (fun (file, file_kind, deps) ->
-    let modname = Filename.chop_extension (Filename.basename file) in
-    modname.[0] <- Char.uppercase modname.[0];
+    let modname =
+      String.capitalize (Filename.chop_extension (Filename.basename file))
+    in
     let key = (modname, file_kind) in
     let new_deps = ref [] in
     Hashtbl.add h key (file, new_deps);
diff --git a/tools/ocamlmklib.ml b/tools/ocamlmklib.ml
index 0ef86979b9..77ae57becb 100644
--- a/tools/ocamlmklib.ml
+++ b/tools/ocamlmklib.ml
@@ -215,10 +215,14 @@ let prepostfix pre name post =
 let transl_path s =
   match Sys.os_type with
     | "Win32" ->
+        let s = Bytes.of_string s in
         let rec aux i =
-          if i = String.length s || s.[i] = ' ' then s
-          else (if s.[i] = '/' then s.[i] <- '\\'; aux (i + 1))
-        in aux 0
+          if i = Bytes.length s || Bytes.get s i = ' ' then s
+          else begin
+            if Bytes.get s i = '/' then Bytes.set s i '\\';
+            aux (i + 1)
+          end
+        in Bytes.to_string (aux 0)
     | _ -> s
 
 let build_libs () =
diff --git a/tools/ocamloptp.ml b/tools/ocamloptp.ml
index 69c2887678..dc0aec9bb5 100644
--- a/tools/ocamloptp.ml
+++ b/tools/ocamloptp.ml
@@ -81,12 +81,14 @@ module Options = Main_args.Make_optcomp_options (struct
   let _rectypes = option "-rectypes"
   let _runtime_variant s = option_with_arg "-runtime-variant" s
   let _S = option "-S"
+  let _safe_string = option "-safe-string"
   let _short_paths = option "-short-paths"
   let _strict_sequence = option "-strict-sequence"
   let _shared = option "-shared"
   let _thread = option "-thread"
   let _trans_mod = option "-trans-mod"
   let _unsafe = option "-unsafe"
+  let _unsafe_string = option "-unsafe-string"
   let _v = option "-v"
   let _version = option "-version"
   let _vnum = option "-vnum"
diff --git a/tools/ocamlprof.ml b/tools/ocamlprof.ml
index 1fde3fe495..478332a6f0 100644
--- a/tools/ocamlprof.ml
+++ b/tools/ocamlprof.ml
@@ -35,7 +35,7 @@ and inchan = ref stdin
 and outchan = ref stdout
 
 (* To copy source fragments *)
-let copy_buffer = String.create 256
+let copy_buffer = Bytes.create 256
 
 let copy_chars_unix nchars =
   let n = ref nchars in
diff --git a/toplevel/topdirs.ml b/toplevel/topdirs.ml
index c8da35b21e..f9d383380e 100644
--- a/toplevel/topdirs.ml
+++ b/toplevel/topdirs.ml
@@ -75,7 +75,7 @@ let load_compunit ic filename ppf compunit =
   let code_size = compunit.cu_codesize + 8 in
   let code = Meta.static_alloc code_size in
   unsafe_really_input ic code 0 compunit.cu_codesize;
-  String.unsafe_set code compunit.cu_codesize (Char.chr Opcodes.opRETURN);
+  Bytes.unsafe_set code compunit.cu_codesize (Char.chr Opcodes.opRETURN);
   String.unsafe_blit "\000\000\000\001\000\000\000" 0
                      code (compunit.cu_codesize + 1) 7;
   let initial_symtable = Symtable.current_state() in
@@ -110,7 +110,7 @@ let rec load_file recursive ppf name =
 
 and really_load_file recursive ppf name filename ic =
   let ic = open_in_bin filename in
-  let buffer = Misc.input_bytes ic (String.length Config.cmo_magic_number) in
+  let buffer = really_input_string ic (String.length Config.cmo_magic_number) in
   try
     if buffer = Config.cmo_magic_number then begin
       let compunit_pos = input_binary_int ic in  (* Go to descriptor *)
diff --git a/toplevel/toploop.ml b/toplevel/toploop.ml
index 0671fb3a9b..e991ee6490 100644
--- a/toplevel/toploop.ml
+++ b/toplevel/toploop.ml
@@ -383,7 +383,7 @@ let read_input_default prompt buffer len =
     while true do
       if !i >= len then raise Exit;
       let c = input_char Pervasives.stdin in
-      buffer.[!i] <- c;
+      Bytes.set buffer !i c;
       incr i;
       if c = '\n' then raise Exit;
     done;
diff --git a/toplevel/toploop.mli b/toplevel/toploop.mli
index 324857a835..19bb885c5e 100644
--- a/toplevel/toploop.mli
+++ b/toplevel/toploop.mli
@@ -101,7 +101,7 @@ val print_out_phrase :
 
 (* Hooks for external line editor *)
 
-val read_interactive_input : (string -> string -> int -> int * bool) ref
+val read_interactive_input : (string -> bytes -> int -> int * bool) ref
 
 (* Hooks for initialization *)
 
diff --git a/toplevel/topmain.ml b/toplevel/topmain.ml
index 0f3ac66f9d..207d749a56 100644
--- a/toplevel/topmain.ml
+++ b/toplevel/topmain.ml
@@ -76,11 +76,13 @@ module Options = Main_args.Make_bytetop_options (struct
   let _ppx s = first_ppx := s :: !first_ppx
   let _principal = set principal
   let _rectypes = set recursive_types
+  let _safe_string = clear unsafe_string
   let _short_paths = clear real_paths
   let _stdin () = file_argument ""
   let _strict_sequence = set strict_sequence
   let _trans_mod = set transparent_modules
   let _unsafe = set fast
+  let _unsafe_string = set unsafe_string
   let _version () = print_version ()
   let _vnum () = print_version_num ()
   let _w s = Warnings.parse_options false s
diff --git a/typing/cmi_format.ml b/typing/cmi_format.ml
index e5a8399fac..00358b66a7 100644
--- a/typing/cmi_format.ml
+++ b/typing/cmi_format.ml
@@ -40,7 +40,9 @@ let input_cmi ic =
 let read_cmi filename =
   let ic = open_in_bin filename in
   try
-    let buffer = Misc.input_bytes ic (String.length Config.cmi_magic_number) in
+    let buffer =
+      really_input_string ic (String.length Config.cmi_magic_number)
+    in
     if buffer <> Config.cmi_magic_number then begin
       close_in ic;
       let pre_len = String.length Config.cmi_magic_number - 3 in
diff --git a/typing/cmt_format.ml b/typing/cmt_format.ml
index 29751de8f7..f07e442568 100644
--- a/typing/cmt_format.ml
+++ b/typing/cmt_format.ml
@@ -23,9 +23,7 @@ open Typedtree
 
 let read_magic_number ic =
   let len_magic_number = String.length Config.cmt_magic_number in
-  let magic_number = String.create len_magic_number in
-  really_input ic magic_number 0 len_magic_number;
-  magic_number
+  really_input_string ic len_magic_number
 
 type binary_annots =
   | Packed of Types.signature * string list
diff --git a/typing/ctype.ml b/typing/ctype.ml
index cd468fde9b..ac15c10697 100644
--- a/typing/ctype.ml
+++ b/typing/ctype.ml
@@ -242,7 +242,7 @@ let in_current_module = function
 
 let in_pervasives p =
   in_current_module p &&
-  try ignore (Env.find_type p Env.initial); true
+  try ignore (Env.find_type p Env.initial_safe_string); true
   with Not_found -> false
 
 let is_datatype decl=
diff --git a/typing/env.ml b/typing/env.ml
index 381733876b..7e904fc9fe 100644
--- a/typing/env.ml
+++ b/typing/env.ml
@@ -1700,8 +1700,7 @@ and fold_cltypes f =
 
 
 (* Make the initial environment *)
-
-let initial =
+let (initial_safe_string, initial_unsafe_string) =
   Predef.build_initial_env
     (add_type ~check:false)
     (add_exception ~check:false)
diff --git a/typing/env.mli b/typing/env.mli
index 888869ebfc..f5ef302b3c 100644
--- a/typing/env.mli
+++ b/typing/env.mli
@@ -29,7 +29,8 @@ type summary =
 type t
 
 val empty: t
-val initial: t
+val initial_safe_string: t
+val initial_unsafe_string: t
 val diff: t -> t -> Ident.t list
 
 type type_descriptions =
diff --git a/typing/includemod.ml b/typing/includemod.ml
index 2b315655a8..54aca4a7c4 100644
--- a/typing/includemod.ml
+++ b/typing/includemod.ml
@@ -401,9 +401,9 @@ let _ = Env.check_modtype_inclusion := check_modtype_inclusion
 (* Check that an implementation of a compilation unit meets its
    interface. *)
 
-let compunit impl_name impl_sig intf_name intf_sig =
+let compunit env impl_name impl_sig intf_name intf_sig =
   try
-    signatures Env.initial [] Subst.identity impl_sig intf_sig
+    signatures env [] Subst.identity impl_sig intf_sig
   with Error reasons ->
     raise(Error(([], Env.empty,Interface_mismatch(impl_name, intf_name))
                 :: reasons))
@@ -535,12 +535,12 @@ let include_err ppf (cxt, env, err) =
   Printtyp.wrap_printing_env env (fun () ->
     fprintf ppf "@[<v>%a%a@]" context (List.rev cxt) include_err err)
 
-let buffer = ref ""
+let buffer = ref Bytes.empty
 let is_big obj =
   let size = !Clflags.error_size in
   size > 0 &&
   begin
-    if String.length !buffer < size then buffer := String.create size;
+    if Bytes.length !buffer < size then buffer := Bytes.create size;
     try ignore (Marshal.to_buffer !buffer 0 size obj []); false
     with _ -> true
   end
diff --git a/typing/includemod.mli b/typing/includemod.mli
index 2e00bb0246..b3801ccd3d 100644
--- a/typing/includemod.mli
+++ b/typing/includemod.mli
@@ -18,7 +18,8 @@ open Format
 
 val modtypes: Env.t -> module_type -> module_type -> module_coercion
 val signatures: Env.t -> signature -> signature -> module_coercion
-val compunit: string -> signature -> string -> signature -> module_coercion
+val compunit:
+      Env.t -> string -> signature -> string -> signature -> module_coercion
 val type_declarations:
       Env.t -> Ident.t -> type_declaration -> type_declaration -> unit
 
diff --git a/typing/predef.ml b/typing/predef.ml
index 9b95d62642..25b0deb16b 100644
--- a/typing/predef.ml
+++ b/typing/predef.ml
@@ -41,6 +41,7 @@ and ident_nativeint = ident_create "nativeint"
 and ident_int32 = ident_create "int32"
 and ident_int64 = ident_create "int64"
 and ident_lazy_t = ident_create "lazy_t"
+and ident_bytes = ident_create "bytes"
 
 let path_int = Pident ident_int
 and path_char = Pident ident_char
@@ -57,6 +58,7 @@ and path_nativeint = Pident ident_nativeint
 and path_int32 = Pident ident_int32
 and path_int64 = Pident ident_int64
 and path_lazy_t = Pident ident_lazy_t
+and path_bytes = Pident ident_bytes
 
 let type_int = newgenty (Tconstr(path_int, [], ref Mnil))
 and type_char = newgenty (Tconstr(path_char, [], ref Mnil))
@@ -72,6 +74,7 @@ and type_nativeint = newgenty (Tconstr(path_nativeint, [], ref Mnil))
 and type_int32 = newgenty (Tconstr(path_int32, [], ref Mnil))
 and type_int64 = newgenty (Tconstr(path_int64, [], ref Mnil))
 and type_lazy_t t = newgenty (Tconstr(path_lazy_t, [t], ref Mnil))
+and type_bytes = newgenty (Tconstr(path_bytes, [], ref Mnil))
 
 let ident_match_failure = ident_create_predef_exn "Match_failure"
 and ident_out_of_memory = ident_create_predef_exn "Out_of_memory"
@@ -119,7 +122,7 @@ and ident_nil = ident_create "[]"
 and ident_cons = ident_create "::"
 and ident_none = ident_create "None"
 and ident_some = ident_create "Some"
-let build_initial_env add_type add_exception empty_env =
+let common_initial_env add_type add_exception empty_env =
   let decl_bool =
     {decl_abstr with
      type_kind = Type_variant([cstr ident_false []; cstr ident_true []])}
@@ -200,6 +203,13 @@ let build_initial_env add_type add_exception empty_env =
   add_type ident_int decl_abstr (
     empty_env)))))))))))))))))))))))))))
 
+let build_initial_env add_type add_exception empty_env =
+  let common = common_initial_env add_type add_exception empty_env in
+  let safe_string = add_type ident_bytes decl_abstr common in
+  let decl_bytes_unsafe = {decl_abstr with type_manifest = Some type_string} in
+  let unsafe_string = add_type ident_bytes decl_bytes_unsafe common in
+  (safe_string, unsafe_string)
+
 let builtin_values =
   List.map (fun id -> Ident.make_global id; (Ident.name id, id))
       [ident_match_failure; ident_out_of_memory; ident_stack_overflow;
diff --git a/typing/predef.mli b/typing/predef.mli
index a2f4724718..ed74ecb61f 100644
--- a/typing/predef.mli
+++ b/typing/predef.mli
@@ -17,6 +17,7 @@ open Types
 val type_int: type_expr
 val type_char: type_expr
 val type_string: type_expr
+val type_bytes: type_expr
 val type_float: type_expr
 val type_bool: type_expr
 val type_unit: type_expr
@@ -32,6 +33,7 @@ val type_lazy_t: type_expr -> type_expr
 val path_int: Path.t
 val path_char: Path.t
 val path_string: Path.t
+val path_bytes: Path.t
 val path_float: Path.t
 val path_bool: Path.t
 val path_unit: Path.t
@@ -56,7 +58,7 @@ val path_undefined_recursive_module : Path.t
 val build_initial_env:
   (Ident.t -> type_declaration -> 'a -> 'a) ->
   (Ident.t -> exception_declaration -> 'a -> 'a) ->
-  'a -> 'a
+  'a -> 'a * 'a
 
 (* To initialize linker tables *)
 
diff --git a/typing/typecore.ml b/typing/typecore.ml
index a9849886bf..03830254d6 100644
--- a/typing/typecore.ml
+++ b/typing/typecore.ml
@@ -257,14 +257,14 @@ let mkexp exp_desc exp_type exp_loc exp_env =
   { exp_desc; exp_type; exp_loc; exp_env; exp_extra = []; exp_attributes = [] }
 
 let option_none ty loc =
-  let lid = Longident.Lident "None" in
-  let cnone = Env.lookup_constructor lid Env.initial in
-  mkexp (Texp_construct(mknoloc lid, cnone, []))
-    ty loc Env.initial
+  let lid = Longident.Lident "None"
+  and env = Env.initial_safe_string in
+  let cnone = Env.lookup_constructor lid env in
+  mkexp (Texp_construct(mknoloc lid, cnone, [])) ty loc env
 
 let option_some texp =
   let lid = Longident.Lident "Some" in
-  let csome = Env.lookup_constructor lid Env.initial in
+  let csome = Env.lookup_constructor lid Env.initial_safe_string in
   mkexp ( Texp_construct(mknoloc lid , csome, [texp]) )
     (type_option texp.exp_type) texp.exp_loc texp.exp_env
 
diff --git a/typing/typemod.ml b/typing/typemod.ml
index feee30b28d..51171ff649 100644
--- a/typing/typemod.ml
+++ b/typing/typemod.ml
@@ -1544,7 +1544,8 @@ let type_implementation sourcefile outputprefix modulename initial_env ast =
           raise(Error(Location.in_file sourcefile, Env.empty,
                       Interface_not_compiled sourceintf)) in
       let dclsig = Env.read_signature modulename intf_file in
-      let coercion = Includemod.compunit sourcefile sg intf_file dclsig in
+      let coercion =
+        Includemod.compunit initial_env sourcefile sg intf_file dclsig in
       Typecore.force_delayed_checks ();
       (* It is important to run these checks after the inclusion test above,
          so that value declarations which are not used internally but exported
@@ -1556,7 +1557,7 @@ let type_implementation sourcefile outputprefix modulename initial_env ast =
       check_nongen_schemes finalenv str.str_items;
       normalize_signature finalenv simple_sg;
       let coercion =
-        Includemod.compunit sourcefile sg
+        Includemod.compunit initial_env sourcefile sg
                             "(inferred signature)" simple_sg in
       Typecore.force_delayed_checks ();
       (* See comment above. Here the target signature contains all
@@ -1601,7 +1602,7 @@ let rec package_signatures subst = function
                  Trec_not) ::
       package_signatures (Subst.add_module oldid (Pident newid) subst) rem
 
-let package_units objfiles cmifile modulename =
+let package_units initial_env objfiles cmifile modulename =
   (* Read the signatures of the units *)
   let units =
     List.map
@@ -1610,7 +1611,7 @@ let package_units objfiles cmifile modulename =
          let modname = String.capitalize(Filename.basename pref) in
          let sg = Env.read_signature modname (pref ^ ".cmi") in
          if Filename.check_suffix f ".cmi" &&
-            not(Mtype.no_code_needed_sig Env.initial sg)
+            not(Mtype.no_code_needed_sig Env.initial_safe_string sg)
          then raise(Error(Location.none, Env.empty,
                           Implementation_is_required f));
          (modname, Env.read_signature modname (pref ^ ".cmi")))
@@ -1628,8 +1629,8 @@ let package_units objfiles cmifile modulename =
     end;
     let dclsig = Env.read_signature modulename cmifile in
     Cmt_format.save_cmt  (prefix ^ ".cmt") modulename
-      (Cmt_format.Packed (sg, objfiles)) None Env.initial None ;
-    Includemod.compunit "(obtained by packing)" sg mlifile dclsig
+      (Cmt_format.Packed (sg, objfiles)) None initial_env  None ;
+    Includemod.compunit initial_env "(obtained by packing)" sg mlifile dclsig
   end else begin
     (* Determine imports *)
     let unit_names = List.map fst units in
@@ -1643,7 +1644,7 @@ let package_units objfiles cmifile modulename =
         Env.save_signature_with_imports sg modulename
           (prefix ^ ".cmi") imports in
       Cmt_format.save_cmt (prefix ^ ".cmt")  modulename
-        (Cmt_format.Packed (sg, objfiles)) None Env.initial (Some sg)
+        (Cmt_format.Packed (sg, objfiles)) None initial_env (Some sg)
     end;
     Tcoerce_none
   end
diff --git a/typing/typemod.mli b/typing/typemod.mli
index 051a283609..a6d5713eee 100644
--- a/typing/typemod.mli
+++ b/typing/typemod.mli
@@ -33,11 +33,12 @@ val check_nongen_schemes:
 
 val simplify_signature: signature -> signature
 
-val save_signature : string -> Typedtree.signature -> string -> string ->
+val save_signature:
+  string -> Typedtree.signature -> string -> string ->
   Env.t -> Types.signature_item list -> unit
 
 val package_units:
-        string list -> string -> string -> Typedtree.module_coercion
+  Env.t -> string list -> string -> string -> Typedtree.module_coercion
 
 type error =
     Cannot_apply of module_type
diff --git a/typing/typetexp.ml b/typing/typetexp.ml
index 44bad48bc6..eacf977c65 100644
--- a/typing/typetexp.ml
+++ b/typing/typetexp.ml
@@ -126,7 +126,7 @@ let find_component lookup make_error env loc lid =
   try
     match lid with
     | Longident.Ldot (Longident.Lident "*predef*", s) ->
-        lookup (Longident.Lident s) Env.initial
+        lookup (Longident.Lident s) Env.initial_safe_string
     | _ -> lookup lid env
   with Not_found ->
     narrow_unbound_lid_error env loc lid make_error
diff --git a/utils/clflags.ml b/utils/clflags.ml
index 90b8a948fd..aa105c774e 100644
--- a/utils/clflags.ml
+++ b/utils/clflags.ml
@@ -107,3 +107,4 @@ let dlcode = ref true (* not -nodynlink *)
 let runtime_variant = ref "";;      (* -runtime-variant *)
 
 let keep_locs = ref false              (* -keep-locs *)
+let unsafe_string = ref true;;         (* -safe-string / -unsafe-string *)
diff --git a/utils/clflags.mli b/utils/clflags.mli
index 489ac4d7b7..41043e69bb 100644
--- a/utils/clflags.mli
+++ b/utils/clflags.mli
@@ -90,3 +90,4 @@ val dlcode : bool ref
 val runtime_variant : string ref
 val force_slash : bool ref
 val keep_locs : bool ref
+val unsafe_string : bool ref
diff --git a/utils/misc.ml b/utils/misc.ml
index 1a2a871394..898880cb07 100644
--- a/utils/misc.ml
+++ b/utils/misc.ml
@@ -124,14 +124,14 @@ let create_hashtable size init =
 (* File copy *)
 
 let copy_file ic oc =
-  let buff = String.create 0x1000 in
+  let buff = Bytes.create 0x1000 in
   let rec copy () =
     let n = input ic buff 0 0x1000 in
     if n = 0 then () else (output oc buff 0 n; copy())
   in copy()
 
 let copy_file_chunk ic oc len =
-  let buff = String.create 0x1000 in
+  let buff = Bytes.create 0x1000 in
   let rec copy n =
     if n <= 0 then () else begin
       let r = input ic buff 0 (min n 0x1000) in
@@ -141,23 +141,13 @@ let copy_file_chunk ic oc len =
 
 let string_of_file ic =
   let b = Buffer.create 0x10000 in
-  let buff = String.create 0x1000 in
+  let buff = Bytes.create 0x1000 in
   let rec copy () =
     let n = input ic buff 0 0x1000 in
     if n = 0 then Buffer.contents b else
-      (Buffer.add_substring b buff 0 n; copy())
+      (Buffer.add_subbytes b buff 0 n; copy())
   in copy()
 
-
-
-(* Reading from a channel *)
-
-let input_bytes ic n =
-  let result = String.create n in
-  really_input ic result 0 n;
-  result
-;;
-
 (* Integer operations *)
 
 let rec log2 n =
@@ -226,26 +216,27 @@ let for4 (_,_,_,x) = x
 
 
 module LongString = struct
-  type t = string array
+  type t = bytes array
 
   let create str_size =
     let tbl_size = str_size / Sys.max_string_length + 1 in
-    let tbl = Array.make tbl_size "" in
+    let tbl = Array.make tbl_size Bytes.empty in
     for i = 0 to tbl_size - 2 do
-      tbl.(i) <- String.create Sys.max_string_length;
+      tbl.(i) <- Bytes.create Sys.max_string_length;
     done;
-    tbl.(tbl_size - 1) <- String.create (str_size mod Sys.max_string_length);
+    tbl.(tbl_size - 1) <- Bytes.create (str_size mod Sys.max_string_length);
     tbl
 
   let length tbl =
     let tbl_size = Array.length tbl in
-    Sys.max_string_length * (tbl_size - 1) + String.length tbl.(tbl_size - 1)
+    Sys.max_string_length * (tbl_size - 1) + Bytes.length tbl.(tbl_size - 1)
 
   let get tbl ind =
-    tbl.(ind / Sys.max_string_length).[ind mod Sys.max_string_length]
+    Bytes.get tbl.(ind / Sys.max_string_length) (ind mod Sys.max_string_length)
 
   let set tbl ind c =
-    tbl.(ind / Sys.max_string_length).[ind mod Sys.max_string_length] <- c
+    Bytes.set tbl.(ind / Sys.max_string_length) (ind mod Sys.max_string_length)
+              c
 
   let blit src srcoff dst dstoff len =
     for i = 0 to len - 1 do
@@ -257,14 +248,14 @@ module LongString = struct
       output_char oc (get tbl i)
     done
 
-  let unsafe_blit_to_string src srcoff dst dstoff len =
+  let unsafe_blit_to_bytes src srcoff dst dstoff len =
     for i = 0 to len - 1 do
-      String.unsafe_set dst (dstoff + i) (get src (srcoff + i))
+      Bytes.unsafe_set dst (dstoff + i) (get src (srcoff + i))
     done
 
   let input_bytes ic len =
     let tbl = create len in
-    Array.iter (fun str -> really_input ic str 0 (String.length str)) tbl;
+    Array.iter (fun str -> really_input ic str 0 (Bytes.length str)) tbl;
     tbl
 end
 
diff --git a/utils/misc.mli b/utils/misc.mli
index 67316365e1..4a3c84b2d9 100644
--- a/utils/misc.mli
+++ b/utils/misc.mli
@@ -66,11 +66,6 @@ val copy_file_chunk: in_channel -> out_channel -> int -> unit
 val string_of_file: in_channel -> string
         (* [string_of_file ic] reads the contents of file [ic] and copies
            them to a string. It stops when encountering EOF on [ic]. *)
-val input_bytes : in_channel -> int -> string;;
-        (* [input_bytes ic n] reads [n] bytes from [ic] and returns them
-           in a new string.  It raises [End_of_file] if EOF is encountered
-           before all the bytes are read. *)
-
 val log2: int -> int
         (* [log2 n] returns [s] such that [n = 1 lsl s]
            if [n] is a power of 2*)
@@ -124,14 +119,14 @@ val for4: 'a * 'b * 'c * 'd -> 'd
 
 module LongString :
   sig
-    type t = string array
+    type t = bytes array
     val create : int -> t
     val length : t -> int
     val get : t -> int -> char
     val set : t -> int -> char -> unit
     val blit : t -> int -> t -> int -> int -> unit
     val output : out_channel -> t -> int -> int -> unit
-    val unsafe_blit_to_string : t -> int -> string -> int -> int -> unit
+    val unsafe_blit_to_bytes : t -> int -> bytes -> int -> int -> unit
     val input_bytes : in_channel -> int -> t
   end