4 files changed, 15 insertions, 4 deletions
diff --git a/perl.c b/perl.c
index 14fda3533f..9d493adae9 100644
--- a/perl.c
+++ b/perl.c
@@ -3565,8 +3565,11 @@ S_init_postdump_symbols(pTHX_ register int argc, register char **argv, register
 #endif /* USE_ENVIRON_ARRAY */
     }
     TAINT_NOT;
-    if ((tmpgv = gv_fetchpv("$",TRUE, SVt_PV)))
+    if ((tmpgv = gv_fetchpv("$",TRUE, SVt_PV))) {
+        SvREADONLY_off(GvSV(tmpgv));
 	sv_setiv(GvSV(tmpgv), (IV)PerlProc_getpid());
+        SvREADONLY_on(GvSV(tmpgv));
+    }
 }
 
 STATIC void
diff --git a/pp_sys.c b/pp_sys.c
index bf2b3522e0..4b9b0963d7 100644
--- a/pp_sys.c
+++ b/pp_sys.c
@@ -3923,8 +3923,11 @@ PP(pp_fork)
 	RETSETUNDEF;
     if (!childpid) {
 	/*SUPPRESS 560*/
-	if ((tmpgv = gv_fetchpv("$", TRUE, SVt_PV)))
+	if ((tmpgv = gv_fetchpv("$", TRUE, SVt_PV))) {
+            SvREADONLY_off(GvSV(tmpgv));
 	    sv_setiv(GvSV(tmpgv), (IV)PerlProc_getpid());
+            SvREADONLY_on(GvSV(tmpgv));
+        }
 	hv_clear(PL_pidstatus);	/* no kids, so don't wait for 'em */
     }
     PUSHi(childpid);
diff --git a/t/op/magic.t b/t/op/magic.t
index 4e47414ae0..4f386231fc 100755
--- a/t/op/magic.t
+++ b/t/op/magic.t
@@ -36,7 +36,7 @@ sub skip {
     return 1;
 }
 
-print "1..43\n";
+print "1..44\n";
 
 $Is_MSWin32 = $^O eq 'MSWin32';
 $Is_NetWare = $^O eq 'NetWare';
@@ -143,6 +143,8 @@ eval { die "foo\n" };
 ok $@ eq "foo\n", $@;
 
 ok $$ > 0, $$;
+eval { $$++ };
+ok $@ =~ /^Modification of a read-only value attempted/;
 
 # $^X and $0
 {
diff --git a/util.c b/util.c
index 4f3e0923f5..01238b865d 100644
--- a/util.c
+++ b/util.c
@@ -2057,8 +2057,11 @@ Perl_my_popen(pTHX_ char *cmd, char *mode)
 	}
 #endif	/* defined OS2 */
 	/*SUPPRESS 560*/
-	if ((tmpgv = gv_fetchpv("$",TRUE, SVt_PV)))
+	if ((tmpgv = gv_fetchpv("$",TRUE, SVt_PV))) {
+        SvREADONLY_off(GvSV(tmpgv));
 	    sv_setiv(GvSV(tmpgv), PerlProc_getpid());
+        SvREADONLY_on(GvSV(tmpgv));
+    }
 	PL_forkprocess = 0;
 	hv_clear(PL_pidstatus);	/* we have no children */
 	return Nullfp;