Re: [PATCH] s/Null(av|ch)/NULL/g

Message-ID: <20060202093849.GD12591@accognoscere.homeunix.org>

p4raw-id: //depot/perl@27054

29 files changed, 225 insertions, 225 deletions

diff --git a/XSUB.h b/XSUB.h
index b3e586c8ae..b7df5e29fd 100644
--- a/XSUB.h
+++ b/XSUB.h
@@ -279,7 +279,7 @@ Rethrows a previously caught exception.  See L<perlguts/"Exception Handling">.
 #  define XS_VERSION_BOOTCHECK \
     STMT_START {							\
 	SV *_sv;							\
-	const char *vn = Nullch, *module = SvPV_nolen_const(ST(0));	\
+	const char *vn = NULL, *module = SvPV_nolen_const(ST(0));	\
 	if (items >= 2)	 /* version supplied as bootstrap arg */	\
 	    _sv = ST(1);						\
 	else {								\
diff --git a/cop.h b/cop.h
index 77b3c239f2..7deceb6040 100644
--- a/cop.h
+++ b/cop.h
@@ -176,21 +176,21 @@ struct cop {
 #  define CopSTASHPV(c)		((c)->cop_stashpv)
 
 #  ifdef NETWARE
-#    define CopSTASHPV_set(c,pv)	((c)->cop_stashpv = ((pv) ? savepv(pv) : Nullch))
+#    define CopSTASHPV_set(c,pv)	((c)->cop_stashpv = ((pv) ? savepv(pv) : NULL))
 #  else
 #    define CopSTASHPV_set(c,pv)	((c)->cop_stashpv = savesharedpv(pv))
 #  endif
 
 #  define CopSTASH(c)		(CopSTASHPV(c) \
 				 ? gv_stashpv(CopSTASHPV(c),GV_ADD) : NULL)
-#  define CopSTASH_set(c,hv)	CopSTASHPV_set(c, (hv) ? HvNAME_get(hv) : Nullch)
+#  define CopSTASH_set(c,hv)	CopSTASHPV_set(c, (hv) ? HvNAME_get(hv) : NULL)
 #  define CopSTASH_eq(c,hv)	((hv) && stashpv_hvname_match(c,hv))
 #  ifdef NETWARE
 #    define CopSTASH_free(c) SAVECOPSTASH_FREE(c)
 #    define CopFILE_free(c) SAVECOPFILE_FREE(c)
 #  else
 #    define CopSTASH_free(c)	PerlMemShared_free(CopSTASHPV(c))
-#    define CopFILE_free(c)	(PerlMemShared_free(CopFILE(c)),(CopFILE(c) = Nullch))
+#    define CopFILE_free(c)	(PerlMemShared_free(CopFILE(c)),(CopFILE(c) = NULL))
 #  endif
 #else
 #  define CopFILEGV(c)		((c)->cop_filegv)
@@ -203,10 +203,10 @@ struct cop {
 #  else
 #    define CopFILEAVx(c)	(GvAV(CopFILEGV(c)))
 # endif
-#  define CopFILE(c)		(CopFILESV(c) ? SvPVX(CopFILESV(c)) : Nullch)
+#  define CopFILE(c)		(CopFILESV(c) ? SvPVX(CopFILESV(c)) : NULL)
 #  define CopSTASH(c)		((c)->cop_stash)
 #  define CopSTASH_set(c,hv)	((c)->cop_stash = (hv))
-#  define CopSTASHPV(c)		(CopSTASH(c) ? HvNAME_get(CopSTASH(c)) : Nullch)
+#  define CopSTASHPV(c)		(CopSTASH(c) ? HvNAME_get(CopSTASH(c)) : NULL)
    /* cop_stash is not refcounted */
 #  define CopSTASHPV_set(c,pv)	CopSTASH_set((c), gv_stashpv(pv,GV_ADD))
 #  define CopSTASH_eq(c,hv)	(CopSTASH(c) == (hv))
diff --git a/doio.c b/doio.c
index 495599cf67..1b04bc2382 100644
--- a/doio.c
+++ b/doio.c
@@ -179,7 +179,7 @@ Perl_do_openn(pTHX_ GV *gv, register const char *oname, I32 len, int as_raw,
 	namesv = sv_2mortal(newSVpv(oname,0));
 	num_svs = 1;
 	svp = &namesv;
-        type = Nullch;
+	type = NULL;
 	fp = PerlIO_openn(aTHX_ type, mode, -1, rawmode, rawperm, NULL, num_svs, svp);
     }
     else {
@@ -381,7 +381,7 @@ Perl_do_openn(pTHX_ GV *gv, register const char *oname, I32 len, int as_raw,
 			    fd = -1;
 		    }
 		    if (!num_svs)
-			type = Nullch;
+			type = NULL;
 		    if (that_fp) {
 			fp = PerlIO_fdupopen(aTHX_ that_fp, NULL, dodup);
 		    }
@@ -412,7 +412,7 @@ Perl_do_openn(pTHX_ GV *gv, register const char *oname, I32 len, int as_raw,
 			namesv = sv_2mortal(newSVpvn(type,tend - type));
 			num_svs = 1;
 			svp = &namesv;
-		        type = Nullch;
+		        type = NULL;
 		    }
 		    fp = PerlIO_openn(aTHX_ type,mode,-1,0,0,NULL,num_svs,svp);
 		}
@@ -450,7 +450,7 @@ Perl_do_openn(pTHX_ GV *gv, register const char *oname, I32 len, int as_raw,
 		    namesv = sv_2mortal(newSVpvn(type,tend - type));
 		    num_svs = 1;
 		    svp = &namesv;
-		    type = Nullch;
+		    type = NULL;
 		}
 		fp = PerlIO_openn(aTHX_ type,mode,-1,0,0,NULL,num_svs,svp);
 	    }
@@ -542,7 +542,7 @@ Perl_do_openn(pTHX_ GV *gv, register const char *oname, I32 len, int as_raw,
 		    namesv = sv_2mortal(newSVpvn(type,tend - type));
 		    num_svs = 1;
 		    svp = &namesv;
-		    type = Nullch;
+		    type = NULL;
 		}
 		fp = PerlIO_openn(aTHX_ type,mode,-1,0,0,NULL,num_svs,svp);
 	    }
@@ -1427,7 +1427,7 @@ Perl_do_execfree(pTHX)
     Safefree(PL_Argv);
     PL_Argv = Null(char **);
     Safefree(PL_Cmd);
-    PL_Cmd = Nullch;
+    PL_Cmd = NULL;
 }
 
 #ifdef PERL_DEFAULT_DO_EXEC3_IMPLEMENTATION
diff --git a/doop.c b/doop.c
index 1d81ca07f6..e84816ae2e 100644
--- a/doop.c
+++ b/doop.c
@@ -1390,7 +1390,7 @@ Perl_do_kv(pTHX)
 	if (PL_op->op_flags & OPf_MOD || LVRET) {	/* lvalue */
 	    if (SvTYPE(TARG) < SVt_PVLV) {
 		sv_upgrade(TARG, SVt_PVLV);
-		sv_magic(TARG, Nullsv, PERL_MAGIC_nkeys, Nullch, 0);
+		sv_magic(TARG, Nullsv, PERL_MAGIC_nkeys, NULL, 0);
 	    }
 	    LvTYPE(TARG) = 'k';
 	    if (LvTARG(TARG) != (SV*)keys) {
diff --git a/dump.c b/dump.c
index 3b7fca4e7c..088e86077f 100644
--- a/dump.c
+++ b/dump.c
@@ -87,7 +87,7 @@ Perl_dump_sub(pTHX_ const GV *gv)
 {
     SV * const sv = sv_newmortal();
 
-    gv_fullname3(sv, gv, Nullch);
+    gv_fullname3(sv, gv, NULL);
     Perl_dump_indent(aTHX_ 0, Perl_debug_log, "\nSUB %s = ", SvPVX_const(sv));
     if (CvXSUB(GvCV(gv)))
 	Perl_dump_indent(aTHX_ 0, Perl_debug_log, "(xsub 0x%"UVxf" %d)\n",
@@ -104,7 +104,7 @@ Perl_dump_form(pTHX_ const GV *gv)
 {
     SV * const sv = sv_newmortal();
 
-    gv_fullname3(sv, gv, Nullch);
+    gv_fullname3(sv, gv, NULL);
     Perl_dump_indent(aTHX_ 0, Perl_debug_log, "\nFORMAT %s = ", SvPVX_const(sv));
     if (CvROOT(GvFORM(gv)))
 	op_dump(CvROOT(GvFORM(gv)));
@@ -772,7 +772,7 @@ Perl_do_op_dump(pTHX_ I32 level, PerlIO *file, const OP *o)
 		SV *tmpsv = newSV(0);
 		ENTER;
 		SAVEFREESV(tmpsv);
-		gv_fullname3(tmpsv, (GV*)cSVOPo->op_sv, Nullch);
+		gv_fullname3(tmpsv, (GV*)cSVOPo->op_sv, NULL);
 		Perl_dump_indent(aTHX_ level, file, "GV = %s\n",
 				 SvPV_nolen_const(tmpsv));
 		LEAVE;
@@ -875,10 +875,10 @@ Perl_gv_dump(pTHX_ GV *gv)
     }
     sv = sv_newmortal();
     PerlIO_printf(Perl_debug_log, "{\n");
-    gv_fullname3(sv, gv, Nullch);
+    gv_fullname3(sv, gv, NULL);
     Perl_dump_indent(aTHX_ 1, Perl_debug_log, "GV_NAME = %s", SvPVX_const(sv));
     if (gv != GvEGV(gv)) {
-	gv_efullname3(sv, GvEGV(gv), Nullch);
+	gv_efullname3(sv, GvEGV(gv), NULL);
 	Perl_dump_indent(aTHX_ 1, Perl_debug_log, "-> %s", SvPVX_const(sv));
     }
     PerlIO_putc(Perl_debug_log, '\n');
@@ -1650,7 +1650,7 @@ Perl_debop(pTHX_ const OP *o)
     case OP_GV:
 	if (cGVOPo_gv) {
 	    SV *sv = newSV(0);
-	    gv_fullname3(sv, cGVOPo_gv, Nullch);
+	    gv_fullname3(sv, cGVOPo_gv, NULL);
 	    PerlIO_printf(Perl_debug_log, "(%s)", SvPV_nolen_const(sv));
 	    SvREFCNT_dec(sv);
 	}
diff --git a/gv.c b/gv.c
index 492c1f3f2f..251d86169d 100644
--- a/gv.c
+++ b/gv.c
@@ -204,7 +204,7 @@ Perl_gv_init(pTHX_ GV *gv, HV *stash, const char *name, STRLEN len, int multi)
     GvFILE(gv) = CopFILE(PL_curcop) ? CopFILE(PL_curcop) : (char *) "";
     GvCVGEN(gv) = 0;
     GvEGV(gv) = gv;
-    sv_magic((SV*)gv, (SV*)gv, PERL_MAGIC_glob, Nullch, 0);
+    sv_magic((SV*)gv, (SV*)gv, PERL_MAGIC_glob, NULL, 0);
     GvSTASH(gv) = stash;
     if (stash)
 	Perl_sv_add_backref(aTHX_ (SV*)stash, (SV*)gv);
@@ -990,7 +990,7 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 		if (strEQ(name2, "SA")) {
 		    AV* const av = GvAVn(gv);
 		    GvMULTI_on(gv);
-		    sv_magic((SV*)av, (SV*)gv, PERL_MAGIC_isa, Nullch, 0);
+		    sv_magic((SV*)av, (SV*)gv, PERL_MAGIC_isa, NULL, 0);
 		    /* NOTE: No support for tied ISA */
 		    if ((add & GV_ADDMULTI) && strEQ(nambeg,"AnyDBM_File::ISA")
 			&& AvFILLp(av) == -1)
@@ -1133,7 +1133,7 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 	case '-':
 	{
 	    AV* const av = GvAVn(gv);
-            sv_magic((SV*)av, Nullsv, PERL_MAGIC_regdata, Nullch, 0);
+            sv_magic((SV*)av, Nullsv, PERL_MAGIC_regdata, NULL, 0);
 	    SvREADONLY_on(av);
 	    goto magicalize;
 	}
@@ -1150,7 +1150,7 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 	case '+':
 	{
 	    AV* const av = GvAVn(gv);
-            sv_magic((SV*)av, (SV*)av, PERL_MAGIC_regdata, Nullch, 0);
+            sv_magic((SV*)av, (SV*)av, PERL_MAGIC_regdata, NULL, 0);
 	    SvREADONLY_on(av);
 	    /* FALL THROUGH */
 	}
diff --git a/hv.c b/hv.c
index 1ede825073..05b3828835 100644
--- a/hv.c
+++ b/hv.c
@@ -1808,7 +1808,7 @@ Perl_hv_undef(pTHX_ HV *hv)
     if ((name = HvNAME_get(hv))) {
         if(PL_stashcache)
 	    hv_delete(PL_stashcache, name, HvNAMELEN_get(hv), G_DISCARD);
-	hv_name_set(hv, Nullch, 0, 0);
+	hv_name_set(hv, NULL, 0, 0);
     }
     SvFLAGS(hv) &= ~SVf_OOK;
     Safefree(HvARRAY(hv));
diff --git a/hv.h b/hv.h
index fd0cf2eda2..8c78c7ad20 100644
--- a/hv.h
+++ b/hv.h
@@ -299,7 +299,7 @@ C<SV*>.
 #define HePV(he,lp)		((HeKLEN(he) == HEf_SVKEY) ?		\
 				 SvPV(HeKEY_sv(he),lp) :		\
 				 (((lp = HeKLEN(he)) >= 0) ?		\
-				  HeKEY(he) : Nullch))
+				  HeKEY(he) : NULL))
 
 #define HeSVKEY(he)		((HeKEY(he) && 				\
 				  HeKLEN(he) == HEf_SVKEY) ?		\
@@ -365,7 +365,7 @@ C<SV*>.
 #define HV_ITERNEXT_WANTPLACEHOLDERS	0x01	/* Don't skip placeholders.  */
 
 #define hv_iternext(hv)	hv_iternext_flags(hv, 0)
-#define hv_magic(hv, gv, how) sv_magic((SV*)(hv), (SV*)(gv), how, Nullch, 0)
+#define hv_magic(hv, gv, how) sv_magic((SV*)(hv), (SV*)(gv), how, NULL, 0)
 
 /* available as a function in hv.c */
 #define Perl_sharepvn(sv, len, hash) HEK_KEY(share_hek(sv, len, hash))
diff --git a/locale.c b/locale.c
index 55da8b1a2a..86b11c841f 100644
--- a/locale.c
+++ b/locale.c
@@ -286,7 +286,7 @@ Perl_init_i18nl10n(pTHX_ int printwarn)
 	if (! (curctype =
 	       setlocale(LC_CTYPE,
 			 (!done && (lang || PerlEnv_getenv("LC_CTYPE")))
-				    ? "" : Nullch)))
+				    ? "" : NULL)))
 	    setlocale_failure = TRUE;
 	else
 	    curctype = savepv(curctype);
@@ -295,7 +295,7 @@ Perl_init_i18nl10n(pTHX_ int printwarn)
 	if (! (curcoll =
 	       setlocale(LC_COLLATE,
 			 (!done && (lang || PerlEnv_getenv("LC_COLLATE")))
-				   ? "" : Nullch)))
+				   ? "" : NULL)))
 	    setlocale_failure = TRUE;
 	else
 	    curcoll = savepv(curcoll);
@@ -304,7 +304,7 @@ Perl_init_i18nl10n(pTHX_ int printwarn)
 	if (! (curnum =
 	       setlocale(LC_NUMERIC,
 			 (!done && (lang || PerlEnv_getenv("LC_NUMERIC")))
-				  ? "" : Nullch)))
+				  ? "" : NULL)))
 	    setlocale_failure = TRUE;
 	else
 	    curnum = savepv(curnum);
@@ -454,13 +454,13 @@ Perl_init_i18nl10n(pTHX_ int printwarn)
 #endif /* ! LC_ALL */
 
 #ifdef USE_LOCALE_CTYPE
-	curctype = savepv(setlocale(LC_CTYPE, Nullch));
+	curctype = savepv(setlocale(LC_CTYPE, NULL));
 #endif /* USE_LOCALE_CTYPE */
 #ifdef USE_LOCALE_COLLATE
-	curcoll = savepv(setlocale(LC_COLLATE, Nullch));
+	curcoll = savepv(setlocale(LC_COLLATE, NULL));
 #endif /* USE_LOCALE_COLLATE */
 #ifdef USE_LOCALE_NUMERIC
-	curnum = savepv(setlocale(LC_NUMERIC, Nullch));
+	curnum = savepv(setlocale(LC_NUMERIC, NULL));
 #endif /* USE_LOCALE_NUMERIC */
     }
     else {
diff --git a/malloc.c b/malloc.c
index 63f6630678..94fcb15632 100644
--- a/malloc.c
+++ b/malloc.c
@@ -1173,7 +1173,7 @@ perl_get_emergency_buffer(IV *size)
     }
 
     SvPOK_off(sv);
-    SvPV_set(sv, Nullch);
+    SvPV_set(sv, NULL);
     SvCUR_set(sv, 0);
     SvLEN_set(sv, 0);
     *size = malloced_size(pv) + M_OVERHEAD;
@@ -1249,7 +1249,7 @@ emergency_sbrk(MEM_SIZE size)
 	if (emergency_buffer_size) {
 	    add_to_chain(emergency_buffer, emergency_buffer_size, 0);
 	    emergency_buffer_size = 0;
-	    emergency_buffer = Nullch;
+	    emergency_buffer = NULL;
 	    have = 1;
 	}
 
@@ -1276,7 +1276,7 @@ emergency_sbrk(MEM_SIZE size)
     MALLOC_UNLOCK;
     emergency_sbrk_croak("Out of memory during request for %"UVuf" bytes, total sbrk() is %"UVuf" bytes", (UV)size, (UV)(goodsbrk + sbrk_slack));
     /* NOTREACHED */
-    return Nullch;
+    return NULL;
 }
 
 #else /*  !defined(PERL_EMERGENCY_SBRK) */
@@ -2141,7 +2141,7 @@ Perl_realloc(void *mp, size_t nbytes)
 		    bad_free_warn = (pbf) ? atoi(pbf) : 1;
 		}
 		if (!bad_free_warn)
-		    return Nullch;
+		    return NULL;
 #ifdef RCHECK
 #ifdef PERL_CORE
 		{
@@ -2169,7 +2169,7 @@ Perl_realloc(void *mp, size_t nbytes)
 		warn("%s", "Bad realloc() ignored");
 #endif
 #endif
-		return Nullch;			/* sanity */
+		return NULL;			/* sanity */
 	    }
 
 	onb = BUCKET_SIZE_REAL(bucket);
diff --git a/mathoms.c b/mathoms.c
index 2acdb420b4..1371667f37 100644
--- a/mathoms.c
+++ b/mathoms.c
@@ -65,7 +65,7 @@ Taint an SV. Use C<SvTAINTED_on> instead.
 void
 Perl_sv_taint(pTHX_ SV *sv)
 {
-    sv_magic((sv), Nullsv, PERL_MAGIC_taint, Nullch, 0);
+    sv_magic((sv), Nullsv, PERL_MAGIC_taint, NULL, 0);
 }
 
 /* sv_2iv() is now a macro using Perl_sv_2iv_flags();
@@ -491,7 +491,7 @@ Perl_hv_iternext(pTHX_ HV *hv)
 void
 Perl_hv_magic(pTHX_ HV *hv, GV *gv, int how)
 {
-    sv_magic((SV*)hv, (SV*)gv, how, Nullch, 0);
+    sv_magic((SV*)hv, (SV*)gv, how, NULL, 0);
 }
 
 #if 0 /* use the macro from hv.h instead */
diff --git a/mg.c b/mg.c
index c2775760d5..a6b4e2f6c1 100644
--- a/mg.c
+++ b/mg.c
@@ -1076,7 +1076,7 @@ Perl_magic_setenv(pTHX_ SV *sv, MAGIC *mg)
 			    return 0;
 			}
 		    }
-		    if ((cp = strchr(elt, ':')) != Nullch)
+		    if ((cp = strchr(elt, ':')) != NULL)
 			*cp = '\0';
 		    if (my_trnlnm(elt, eltbuf, j++))
 			elt = eltbuf;
@@ -1115,7 +1115,7 @@ int
 Perl_magic_clearenv(pTHX_ SV *sv, MAGIC *mg)
 {
     PERL_UNUSED_ARG(sv);
-    my_setenv(MgPV_nolen_const(mg),Nullch);
+    my_setenv(MgPV_nolen_const(mg),NULL);
     return 0;
 }
 
@@ -2206,12 +2206,12 @@ Perl_magic_set(pTHX_ SV *sv, MAGIC *mg)
 	break;
     case '\011':	/* ^I */ /* NOT \t in EBCDIC */
 	Safefree(PL_inplace);
-	PL_inplace = SvOK(sv) ? savesvpv(sv) : Nullch;
+	PL_inplace = SvOK(sv) ? savesvpv(sv) : NULL;
 	break;
     case '\017':	/* ^O */
 	if (*(mg->mg_ptr+1) == '\0') {
 	    Safefree(PL_osname);
-	    PL_osname = Nullch;
+	    PL_osname = NULL;
 	    if (SvOK(sv)) {
 		TAINT_PROPER("assigning to $^O");
 		PL_osname = savesvpv(sv);
@@ -2738,7 +2738,7 @@ Perl_sighandler(int sig)
 	(void)rsignal(sig, PL_csighandlerp);
 #endif
 #endif /* !PERL_MICRO */
-	Perl_die(aTHX_ Nullch);
+	Perl_die(aTHX_ NULL);
     }
 cleanup:
     if (flags & 1)
diff --git a/op.c b/op.c
index e7ed2920e3..6c9b53f575 100644
--- a/op.c
+++ b/op.c
@@ -162,7 +162,7 @@ STATIC const char*
 S_gv_ename(pTHX_ GV *gv)
 {
     SV* const tmpsv = sv_newmortal();
-    gv_efullname3(tmpsv, gv, Nullch);
+    gv_efullname3(tmpsv, gv, NULL);
     return SvPV_nolen_const(tmpsv);
 }
 
@@ -384,7 +384,7 @@ Perl_op_clear(pTHX_ OP *o)
 	}
 	else {
 	    Safefree(cPVOPo->op_pv);
-	    cPVOPo->op_pv = Nullch;
+	    cPVOPo->op_pv = NULL;
 	}
 	break;
     case OP_SUBST:
@@ -3123,9 +3123,9 @@ Perl_utilize(pTHX_ int aver, I32 floor, OP *version, OP *idop, OP *arg)
 	Nullop,
 	append_elem(OP_LINESEQ,
 	    append_elem(OP_LINESEQ,
-	        newSTATEOP(0, Nullch, newUNOP(OP_REQUIRE, 0, idop)),
-	        newSTATEOP(0, Nullch, veop)),
-	    newSTATEOP(0, Nullch, imop) ));
+	        newSTATEOP(0, NULL, newUNOP(OP_REQUIRE, 0, idop)),
+	        newSTATEOP(0, NULL, veop)),
+	    newSTATEOP(0, NULL, imop) ));
 
     /* The "did you use incorrect case?" warning used to be here.
      * The problem is that on case-insensitive filesystems one
@@ -4311,7 +4311,7 @@ Perl_cv_ckproto(pTHX_ const CV *cv, const GV *gv, const char *p)
 	SV* name = Nullsv;
 
 	if (gv)
-	    gv_efullname3(name = sv_newmortal(), gv, Nullch);
+	    gv_efullname3(name = sv_newmortal(), gv, NULL);
 	sv_setpv(msg, "Prototype mismatch:");
 	if (name)
 	    Perl_sv_catpvf(aTHX_ msg, " sub %"SVf, name);
@@ -4471,14 +4471,14 @@ Perl_newATTRSUB(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs, OP *block)
     const I32 gv_fetch_flags
 	= (block || attrs || (CvFLAGS(PL_compcv) & CVf_BUILTIN_ATTRS))
 	? GV_ADDMULTI : GV_ADDMULTI | GV_NOINIT;
-    const char * const name = o ? SvPVx_nolen_const(cSVOPo->op_sv) : Nullch;
+    const char * const name = o ? SvPVx_nolen_const(cSVOPo->op_sv) : NULL;
 
     if (proto) {
 	assert(proto->op_type == OP_CONST);
 	ps = SvPVx_const(((SVOP*)proto)->op_sv, ps_len);
     }
     else
-	ps = Nullch;
+	ps = NULL;
 
     if (!name && PERLDB_NAMEANON && CopLINE(PL_curcop)) {
 	SV * const sv = sv_newmortal();
@@ -4488,7 +4488,7 @@ Perl_newATTRSUB(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs, OP *block)
 	aname = SvPVX_const(sv);
     }
     else
-	aname = Nullch;
+	aname = NULL;
 
     gv = name ? gv_fetchsv(cSVOPo->op_sv, gv_fetch_flags, SVt_PVCV)
 	: gv_fetchpv(aname ? aname
@@ -4695,7 +4695,7 @@ Perl_newATTRSUB(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs, OP *block)
 	/* This makes sub {}; work as expected.  */
 	if (block->op_type == OP_STUB) {
 	    op_free(block);
-	    block = newSTATEOP(0, Nullch, 0);
+	    block = newSTATEOP(0, NULL, 0);
 	}
 	CvROOT(cv) = newUNOP(OP_LEAVESUB, 0, scalarseq(block));
     }
@@ -4729,7 +4729,7 @@ Perl_newATTRSUB(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs, OP *block)
 	    Perl_sv_setpvf(aTHX_ sv, "%s:%ld-%ld",
 			   CopFILE(PL_curcop),
 			   (long)PL_subline, (long)CopLINE(PL_curcop));
-	    gv_efullname3(tmpstr, gv, Nullch);
+	    gv_efullname3(tmpstr, gv, NULL);
 	    hv_store(GvHV(PL_DBsub), SvPVX_const(tmpstr), SvCUR(tmpstr), sv, 0);
 	    hv = GvHVn(db_postponed);
 	    if (HvFILL(hv) > 0 && hv_exists(hv, SvPVX_const(tmpstr), SvCUR(tmpstr))) {
@@ -5413,7 +5413,7 @@ Perl_ck_rvconst(pTHX_ register OP *o)
 	if (SvROK(kidsv) && SvREADONLY(kidsv)) {
 	    SV * const rsv = SvRV(kidsv);
 	    const int svtype = SvTYPE(rsv);
-            const char *badtype = Nullch;
+            const char *badtype = NULL;
 
 	    switch (o->op_type) {
 	    case OP_RV2SV:
@@ -5449,7 +5449,7 @@ Perl_ck_rvconst(pTHX_ register OP *o)
 		o->op_private &= ~HINT_STRICT_REFS;
 	}
 	if ((o->op_private & HINT_STRICT_REFS) && (kid->op_private & OPpCONST_BARE)) {
-            const char *badthing = Nullch;
+            const char *badthing = NULL;
 	    switch (o->op_type) {
 	    case OP_RV2SV:
 		badthing = "a SCALAR";
@@ -5674,7 +5674,7 @@ Perl_ck_fun(pTHX_ OP *o)
 
 			/* is this op a FH constructor? */
 			if (is_handle_constructor(o,numargs)) {
-                            const char *name = Nullch;
+                            const char *name = NULL;
 			    STRLEN len = 0;
 
 			    flags = 0;
@@ -6979,7 +6979,7 @@ Perl_peep(pTHX_ register OP *o)
 		if (SvTYPE(gv) == SVt_PVGV && GvCV(gv) && SvPVX_const(GvCV(gv))) {
 		    /* XXX could check prototype here instead of just carping */
 		    SV * const sv = sv_newmortal();
-		    gv_efullname3(sv, gv, Nullch);
+		    gv_efullname3(sv, gv, NULL);
 		    Perl_warner(aTHX_ packWARN(WARN_PROTOTYPE),
 				"%"SVf"() called too early to check prototype",
 				sv);
diff --git a/op.h b/op.h
index 74bc179812..4e4aa47d7f 100644
--- a/op.h
+++ b/op.h
@@ -355,13 +355,13 @@ struct pmop {
 #  define PmopSTASHPV_set(o,pv)	(PmopSTASHPV(o) = savesharedpv(pv))
 #  define PmopSTASH(o)		(PmopSTASHPV(o) \
 				 ? gv_stashpv(PmopSTASHPV(o),GV_ADD) : NULL)
-#  define PmopSTASH_set(o,hv)	PmopSTASHPV_set(o, ((hv) ? HvNAME_get(hv) : Nullch))
+#  define PmopSTASH_set(o,hv)	PmopSTASHPV_set(o, ((hv) ? HvNAME_get(hv) : NULL))
 #  define PmopSTASH_free(o)	PerlMemShared_free(PmopSTASHPV(o))
 
 #else
 #  define PmopSTASH(o)		((o)->op_pmstash)
 #  define PmopSTASH_set(o,hv)	((o)->op_pmstash = (hv))
-#  define PmopSTASHPV(o)	(PmopSTASH(o) ? HvNAME_get(PmopSTASH(o)) : Nullch)
+#  define PmopSTASHPV(o)	(PmopSTASH(o) ? HvNAME_get(PmopSTASH(o)) : NULL)
    /* op_pmstash is not refcounted */
 #  define PmopSTASHPV_set(o,pv)	PmopSTASH_set((o), gv_stashpv(pv,GV_ADD))
 #  define PmopSTASH_free(o)    
diff --git a/pad.c b/pad.c
index 4211b11f6c..c17bcf6190 100644
--- a/pad.c
+++ b/pad.c
@@ -1532,7 +1532,7 @@ Perl_cv_clone(pTHX_ CV *proto)
 	SV* const const_sv = op_const_sv(CvSTART(cv), cv);
 	if (const_sv) {
 	    SvREFCNT_dec(cv);
-	    cv = newCONSTSUB(CvSTASH(proto), Nullch, const_sv);
+	    cv = newCONSTSUB(CvSTASH(proto), NULL, const_sv);
 	}
 	else {
 	    CvCONST_off(cv);
diff --git a/perl.c b/perl.c
index 9aa2a90ead..26382e9736 100644
--- a/perl.c
+++ b/perl.c
@@ -866,7 +866,7 @@ perl_destruct(pTHXx)
     PL_unsafe       = FALSE;
 
     Safefree(PL_inplace);
-    PL_inplace = Nullch;
+    PL_inplace = NULL;
     SvREFCNT_dec(PL_patchlevel);
 
     if (PL_e_script) {
@@ -889,7 +889,7 @@ perl_destruct(pTHXx)
 
     PL_multiline = 0;		/* $* */
     Safefree(PL_osname);	/* $^O */
-    PL_osname = Nullch;
+    PL_osname = NULL;
 
     SvREFCNT_dec(PL_statname);
     PL_statname = Nullsv;
@@ -907,7 +907,7 @@ perl_destruct(pTHXx)
 
     /* float buffer */
     Safefree(PL_efloatbuf);
-    PL_efloatbuf = Nullch;
+    PL_efloatbuf = NULL;
     PL_efloatsize = 0;
 
     /* startup and shutdown function lists */
@@ -970,12 +970,12 @@ perl_destruct(pTHXx)
     /* free locale stuff */
 #ifdef USE_LOCALE_COLLATE
     Safefree(PL_collation_name);
-    PL_collation_name = Nullch;
+    PL_collation_name = NULL;
 #endif
 
 #ifdef USE_LOCALE_NUMERIC
     Safefree(PL_numeric_name);
-    PL_numeric_name = Nullch;
+    PL_numeric_name = NULL;
     SvREFCNT_dec(PL_numeric_radix_sv);
     PL_numeric_radix_sv = Nullsv;
 #endif
@@ -1213,7 +1213,7 @@ perl_destruct(pTHXx)
     SvREADONLY_off(&PL_sv_undef);
 
     Safefree(PL_origfilename);
-    PL_origfilename = Nullch;
+    PL_origfilename = NULL;
     Safefree(PL_reg_start_tmp);
     PL_reg_start_tmp = (char**)NULL;
     PL_reg_start_tmpl = 0;
@@ -1226,7 +1226,7 @@ perl_destruct(pTHXx)
     Safefree(PL_psig_name);
     PL_psig_name = (SV**)NULL;
     Safefree(PL_bitcount);
-    PL_bitcount = Nullch;
+    PL_bitcount = NULL;
     Safefree(PL_psig_pend);
     PL_psig_pend = (int*)NULL;
     PL_formfeed = Nullsv;
@@ -1498,7 +1498,7 @@ setuid perl scripts securely.\n");
 		   s = PL_origenviron[0];
 		   while (*s) s++;
 #endif
-		   my_setenv("NoNe  SuCh", Nullch);
+		   my_setenv("NoNe  SuCh", NULL);
 		   /* Force copy of environment. */
 		   for (i = 1; PL_origenviron[i]; i++) {
 			if (PL_origenviron[i] == s + 1
@@ -1589,7 +1589,7 @@ S_parse_body(pTHX_ char **env, XSINIT_t xsinit)
     const char *validarg = "";
     register SV *sv;
     register char *s;
-    const char *cddir = Nullch;
+    const char *cddir = NULL;
 #ifdef USE_SITECUSTOMIZE
     bool minus_f = FALSE;
 #endif
@@ -1698,7 +1698,7 @@ S_parse_body(pTHX_ char **env, XSINIT_t xsinit)
 
 	case 'I':	/* -I handled both here and in moreswitches() */
 	    forbid_setid("-I");
-	    if (!*++s && (s=argv[1]) != Nullch) {
+	    if (!*++s && (s=argv[1]) != NULL) {
 		argc--,argv++;
 	    }
 	    if (s && *s) {
@@ -1951,7 +1951,7 @@ S_parse_body(pTHX_ char **env, XSINIT_t xsinit)
             PL_taint_warn = FALSE;
 	}
 	else {
-	    char *popt_copy = Nullch;
+	    char *popt_copy = NULL;
 	    while (s && *s) {
 	        char *d;
 		while (isSPACE(*s))
@@ -2008,7 +2008,7 @@ S_parse_body(pTHX_ char **env, XSINIT_t xsinit)
 	argc++,argv--;
 	scriptname = BIT_BUCKET;	/* don't look for script or read stdin */
     }
-    else if (scriptname == Nullch) {
+    else if (scriptname == NULL) {
 #ifdef MSDOS
 	if ( PerlLIO_isatty(PerlIO_fileno(PerlIO_stdin())) )
 	    moreswitches("h");
@@ -3369,7 +3369,7 @@ Internet, point your browser at http://www.perl.org/, the Perl Home Page.\n\n");
     default:
 	Perl_croak(aTHX_ "Can't emulate -%.1s on #! line",s);
     }
-    return Nullch;
+    return NULL;
 }
 
 /* compliments of Tom Christiansen */
@@ -3947,7 +3947,7 @@ S_validate_suid(pTHX_ const char *validarg, const char *scriptname)
 	PL_doswitches = FALSE;		/* -s is insecure in suid */
 	/* PSz 13 Nov 03  But -s was caught elsewhere ... so unsetting it here is useless(?!) */
 	CopLINE_inc(PL_curcop);
-	if (sv_gets(PL_linestr, PL_rsfp, 0) == Nullch)
+	if (sv_gets(PL_linestr, PL_rsfp, 0) == NULL)
 	    Perl_croak(aTHX_ "No #! line");
 	linestr = SvPV_nolen_const(PL_linestr);
 	/* required even on Sys V */
@@ -4230,7 +4230,7 @@ S_find_beginning(pTHX)
     /* Since the Mac OS does not honor #! arguments for us, we do it ourselves */
 
     while (PL_doextract || gMacPerl_AlwaysExtract) {
-	if ((s = sv_gets(PL_linestr, PL_rsfp, 0)) == Nullch) {
+	if ((s = sv_gets(PL_linestr, PL_rsfp, 0)) == NULL) {
 	    if (!gMacPerl_AlwaysExtract)
 		Perl_croak(aTHX_ "No Perl script found in input\n");
 
@@ -4247,7 +4247,7 @@ S_find_beginning(pTHX)
 	}
 #else
     while (PL_doextract) {
-	if ((s = sv_gets(PL_linestr, PL_rsfp, 0)) == Nullch)
+	if ((s = sv_gets(PL_linestr, PL_rsfp, 0)) == NULL)
 	    Perl_croak(aTHX_ "No Perl script found in input\n");
 #endif
 	s2 = s;
@@ -4613,7 +4613,7 @@ S_init_postdump_symbols(pTHX_ register int argc, register char **argv, register
 #  endif
 	   )
 	{
-	    environ[0] = Nullch;
+	    environ[0] = NULL;
 	}
 	if (env) {
           char** origenv = environ;
@@ -4847,14 +4847,14 @@ S_incpush(pTHX_ const char *dir, bool addsubdirs, bool addoldvers, bool usesep,
 	    }
 	}
 
-	if ( usesep && (s = strchr(p, PERLLIB_SEP)) != Nullch ) {
+	if ( usesep && (s = strchr(p, PERLLIB_SEP)) != NULL ) {
 	    sv_setpvn(libdir, PERLLIB_MANGLE(p, (STRLEN)(s - p)),
 		      (STRLEN)(s - p));
 	    p = s + 1;
 	}
 	else {
 	    sv_setpv(libdir, PERLLIB_MANGLE(p, 0));
-	    p = Nullch;	/* break out */
+	    p = NULL;	/* break out */
 	}
 #ifdef MACOS_TRADITIONAL
 	if (!strchr(SvPVX(libdir), ':')) {
@@ -4978,7 +4978,7 @@ S_incpush(pTHX_ const char *dir, bool addsubdirs, bool addoldvers, bool usesep,
 	    char *unix;
 	    STRLEN len;
 
-	    if ((unix = tounixspec_ts(SvPV(libdir,len),Nullch)) != Nullch) {
+	    if ((unix = tounixspec_ts(SvPV(libdir,len),NULL)) != NULL) {
 		len = strlen(unix);
 		while (unix[len-1] == '/') len--;  /* Cosmetic */
 		sv_usepvn(libdir,unix,len);
diff --git a/perl.h b/perl.h
index 04b070f48a..37ba21022e 100644
--- a/perl.h
+++ b/perl.h
@@ -422,7 +422,7 @@ register struct op *Perl_op asm(stringify(OP_IN_REGISTER));
 #define TAINT_NOT	(PL_tainted = FALSE)
 #define TAINT_IF(c)	if (c) { PL_tainted = TRUE; }
 #define TAINT_ENV()	if (PL_tainting) { taint_env(); }
-#define TAINT_PROPER(s)	if (PL_tainting) { taint_proper(Nullch, s); }
+#define TAINT_PROPER(s)	if (PL_tainting) { taint_proper(NULL, s); }
 
 /* XXX All process group stuff is handled in pp_sys.c.  Should these
    defines move there?  If so, I could simplify this a lot. --AD  9/96.
diff --git a/perlio.c b/perlio.c
index cb7f62b623..bee91ee8dc 100644
--- a/perlio.c
+++ b/perlio.c
@@ -928,7 +928,7 @@ PerlIO_parse_layers(pTHX_ PerlIO_list_t *av, const char *names)
 	    if (*s) {
 		STRLEN llen = 0;
 		const char *e = s;
-		const char *as = Nullch;
+		const char *as = NULL;
 		STRLEN alen = 0;
 		if (!isIDFIRST(*s)) {
 		    /*
@@ -1095,7 +1095,7 @@ PerlIO_default_layers(pTHX)
 {
     dVAR;
     if (!PL_def_layerlist) {
-	const char * const s = (PL_tainting) ? Nullch : PerlEnv_getenv("PERLIO");
+	const char * const s = (PL_tainting) ? NULL : PerlEnv_getenv("PERLIO");
 	PERLIO_FUNCS_DECL(*osLayer) = &PerlIO_unix;
 	PL_def_layerlist = PerlIO_list_alloc(aTHX);
 	PerlIO_define_layer(aTHX_ PERLIO_FUNCS_CAST(&PerlIO_unix));
@@ -1357,7 +1357,7 @@ PerlIO_binmode(pTHX_ PerlIO *f, int iotype, int mode, const char *names)
 	/* Legacy binmode is now _defined_ as being equivalent to pushing :raw
 	   So code that used to be here is now in PerlIORaw_pushed().
 	 */
-	return PerlIO_push(aTHX_ f, PERLIO_FUNCS_CAST(&PerlIO_raw), Nullch, Nullsv) ? TRUE : FALSE;
+	return PerlIO_push(aTHX_ f, PERLIO_FUNCS_CAST(&PerlIO_raw), NULL, Nullsv) ? TRUE : FALSE;
     }
 }
 
@@ -3229,7 +3229,7 @@ PerlIOStdio_setlinebuf(pTHX_ PerlIO *f)
 #ifdef HAS_SETLINEBUF
     PerlSIO_setlinebuf(PerlIOSelf(f, PerlIOStdio)->stdio);
 #else
-    PerlSIO_setvbuf(PerlIOSelf(f, PerlIOStdio)->stdio, Nullch, _IOLBF, 0);
+    PerlSIO_setvbuf(PerlIOSelf(f, PerlIOStdio)->stdio, NULL, _IOLBF, 0);
 #endif
 }
 
@@ -3461,7 +3461,7 @@ PerlIO_findFILE(PerlIO *f)
 	l = *PerlIONext(&l);
     }
     /* Uses fallback "mode" via PerlIO_modestr() in PerlIO_exportFILE */
-    return PerlIO_exportFILE(f, Nullch);
+    return PerlIO_exportFILE(f, NULL);
 }
 
 /* Use this to reverse PerlIO_exportFILE calls. */
@@ -3555,7 +3555,7 @@ PerlIOBuf_open(pTHX_ PerlIO_funcs *self, PerlIO_list_t *layers,
 #ifdef PERLIO_USING_CRLF
 #  ifdef PERLIO_IS_BINMODE_FD
 		if (PERLIO_IS_BINMODE_FD(fd))
-		    PerlIO_binmode(aTHX_ f,  '<'/*not used*/, O_BINARY, Nullch);
+		    PerlIO_binmode(aTHX_ f,  '<'/*not used*/, O_BINARY, NULL);
 		else
 #  endif
 		/*
@@ -4792,7 +4792,7 @@ PerlIO_getname(PerlIO *f, char *buf)
     PERL_UNUSED_ARG(f);
     PERL_UNUSED_ARG(buf);
     Perl_croak(aTHX_ "Don't know how to get file name");
-    return Nullch;
+    return NULL;
 #endif
 }
 
@@ -4808,7 +4808,7 @@ PerlIO *
 PerlIO_fdopen(int fd, const char *mode)
 {
     dTHX;
-    return PerlIO_openn(aTHX_ Nullch, mode, fd, 0, 0, NULL, 0, NULL);
+    return PerlIO_openn(aTHX_ NULL, mode, fd, 0, 0, NULL, 0, NULL);
 }
 
 #undef PerlIO_open
@@ -4817,7 +4817,7 @@ PerlIO_open(const char *path, const char *mode)
 {
     dTHX;
     SV *name = sv_2mortal(newSVpv(path, 0));
-    return PerlIO_openn(aTHX_ Nullch, mode, -1, 0, 0, NULL, 1, &name);
+    return PerlIO_openn(aTHX_ NULL, mode, -1, 0, 0, NULL, 1, &name);
 }
 
 #undef Perlio_reopen
@@ -4826,7 +4826,7 @@ PerlIO_reopen(const char *path, const char *mode, PerlIO *f)
 {
     dTHX;
     SV *name = sv_2mortal(newSVpv(path,0));
-    return PerlIO_openn(aTHX_ Nullch, mode, -1, 0, 0, f, 1, &name);
+    return PerlIO_openn(aTHX_ NULL, mode, -1, 0, 0, f, 1, &name);
 }
 
 #undef PerlIO_getc
diff --git a/perlsdio.h b/perlsdio.h
index c35752abbd..480b024db1 100644
--- a/perlsdio.h
+++ b/perlsdio.h
@@ -87,7 +87,7 @@
 #ifdef HAS_SETLINEBUF
 #define PerlIO_setlinebuf(f)		PerlSIO_setlinebuf(f);
 #else
-#define PerlIO_setlinebuf(f)		PerlSIO_setvbuf(f, Nullch, _IOLBF, 0);
+#define PerlIO_setlinebuf(f)		PerlSIO_setvbuf(f, NULL, _IOLBF, 0);
 #endif
 
 /* Now our interface to Configure's FILE_xxx macros */
diff --git a/pod/perlapi.pod b/pod/perlapi.pod
index 5d807df536..a97032971e 100644
--- a/pod/perlapi.pod
+++ b/pod/perlapi.pod
@@ -2163,7 +2163,7 @@ Found in file util.c
 X<fbm_instr>
 
 Returns the location of the SV in the string delimited by C<str> and
-C<strend>.  It returns C<Nullch> if the string can't be found.  The C<sv>
+C<strend>.  It returns C<NULL> if the string can't be found.  The C<sv>
 does not have to be fbm_compiled, but the search will not be as fast
 then.
 
@@ -5399,7 +5399,7 @@ X<sv_setref_iv>
 Copies an integer into a new SV, optionally blessing the SV.  The C<rv>
 argument will be upgraded to an RV.  That RV will be modified to point to
 the new SV.  The C<classname> argument indicates the package for the
-blessing.  Set C<classname> to C<Nullch> to avoid the blessing.  The new SV
+blessing.  Set C<classname> to C<NULL> to avoid the blessing.  The new SV
 will have a reference count of 1, and the RV will be returned.
 
 	SV*	sv_setref_iv(SV* rv, const char* classname, IV iv)
@@ -5413,7 +5413,7 @@ X<sv_setref_nv>
 Copies a double into a new SV, optionally blessing the SV.  The C<rv>
 argument will be upgraded to an RV.  That RV will be modified to point to
 the new SV.  The C<classname> argument indicates the package for the
-blessing.  Set C<classname> to C<Nullch> to avoid the blessing.  The new SV
+blessing.  Set C<classname> to C<NULL> to avoid the blessing.  The new SV
 will have a reference count of 1, and the RV will be returned.
 
 	SV*	sv_setref_nv(SV* rv, const char* classname, NV nv)
@@ -5428,7 +5428,7 @@ Copies a pointer into a new SV, optionally blessing the SV.  The C<rv>
 argument will be upgraded to an RV.  That RV will be modified to point to
 the new SV.  If the C<pv> argument is NULL then C<PL_sv_undef> will be placed
 into the SV.  The C<classname> argument indicates the package for the
-blessing.  Set C<classname> to C<Nullch> to avoid the blessing.  The new SV
+blessing.  Set C<classname> to C<NULL> to avoid the blessing.  The new SV
 will have a reference count of 1, and the RV will be returned.
 
 Do not use with other Perl types such as HV, AV, SV, CV, because those
@@ -5448,7 +5448,7 @@ Copies a string into a new SV, optionally blessing the SV.  The length of the
 string must be specified with C<n>.  The C<rv> argument will be upgraded to
 an RV.  That RV will be modified to point to the new SV.  The C<classname>
 argument indicates the package for the blessing.  Set C<classname> to
-C<Nullch> to avoid the blessing.  The new SV will have a reference count
+C<NULL> to avoid the blessing.  The new SV will have a reference count
 of 1, and the RV will be returned.
 
 Note that C<sv_setref_pv> copies the pointer while this copies the string.
@@ -5464,7 +5464,7 @@ X<sv_setref_uv>
 Copies an unsigned integer into a new SV, optionally blessing the SV.  The C<rv>
 argument will be upgraded to an RV.  That RV will be modified to point to
 the new SV.  The C<classname> argument indicates the package for the
-blessing.  Set C<classname> to C<Nullch> to avoid the blessing.  The new SV
+blessing.  Set C<classname> to C<NULL> to avoid the blessing.  The new SV
 will have a reference count of 1, and the RV will be returned.
 
 	SV*	sv_setref_uv(SV* rv, const char* classname, UV uv)
@@ -6502,11 +6502,11 @@ function.  Calling C<croak> returns control directly to Perl,
 sidestepping the normal C order of execution. See C<warn>.
 
 If you want to throw an exception object, assign the object to
-C<$@> and then pass C<Nullch> to croak():
+C<$@> and then pass C<NULL> to croak():
 
    errsv = get_sv("@", TRUE);
    sv_setsv(errsv, exception_object);
-   croak(Nullch);
+   croak(NULL);
 
 	void	croak(const char* pat, ...)
 
diff --git a/pp_sort.c b/pp_sort.c
index 868d6ab1e4..aa363c622b 100644
--- a/pp_sort.c
+++ b/pp_sort.c
@@ -1520,7 +1520,7 @@ PP(pp_sort)
 		}
 		else if (gv) {
 		    SV *tmpstr = sv_newmortal();
-		    gv_efullname3(tmpstr, gv, Nullch);
+		    gv_efullname3(tmpstr, gv, NULL);
 		    DIE(aTHX_ "Undefined sort subroutine \"%"SVf"\" called",
 			tmpstr);
 		}
diff --git a/pp_sys.c b/pp_sys.c
index 4470aa6226..8b99106aeb 100644
--- a/pp_sys.c
+++ b/pp_sys.c
@@ -344,7 +344,7 @@ PP(pp_backtick)
 	    SAVESPTR(PL_rs);
 	    PL_rs = &PL_sv_undef;
 	    sv_setpvn(TARG, "", 0);	/* note that this preserves previous buffer */
-	    while (sv_gets(TARG, fp, SvCUR(TARG)) != Nullch)
+	    while (sv_gets(TARG, fp, SvCUR(TARG)) != NULL)
 		;
 	    LEAVE;
 	    XPUSHs(TARG);
@@ -353,7 +353,7 @@ PP(pp_backtick)
 	else {
 	    for (;;) {
 		SV * const sv = newSV(79);
-		if (sv_gets(sv, fp, 0) == Nullch) {
+		if (sv_gets(sv, fp, 0) == NULL) {
 		    SvREFCNT_dec(sv);
 		    break;
 		}
@@ -477,7 +477,7 @@ PP(pp_die)
     }
     else {
 	tmpsv = TOPs;
-        tmps = SvROK(tmpsv) ? Nullch : SvPV_const(tmpsv, len);
+        tmps = SvROK(tmpsv) ? NULL : SvPV_const(tmpsv, len);
     }
     if (!tmps || !len) {
 	SV * const error = ERRSV;
@@ -502,7 +502,7 @@ PP(pp_die)
 		    sv_setsv(error,*PL_stack_sp--);
 		}
 	    }
-	    DIE(aTHX_ Nullch);
+	    DIE(aTHX_ NULL);
 	}
 	else {
 	    if (SvPOK(error) && SvCUR(error))
@@ -511,7 +511,7 @@ PP(pp_die)
 	    if (SvOK(tmpsv))
 		tmps = SvPV_const(tmpsv, len);
 	    else
-		tmps = Nullch;
+		tmps = NULL;
 	}
     }
     if (!tmps || !len)
@@ -761,11 +761,11 @@ PP(pp_binmode)
 
     PUTBACK;
     if (PerlIO_binmode(aTHX_ fp,IoTYPE(io),mode_from_discipline(discp),
-                       (discp) ? SvPV_nolen_const(discp) : Nullch)) {
+                       (discp) ? SvPV_nolen_const(discp) : NULL)) {
 	if (IoOFP(io) && IoOFP(io) != IoIFP(io)) {
 	     if (!PerlIO_binmode(aTHX_ IoOFP(io),IoTYPE(io),
 			mode_from_discipline(discp),
-                       (discp) ? SvPV_nolen_const(discp) : Nullch)) {
+                       (discp) ? SvPV_nolen_const(discp) : NULL)) {
 		SPAGAIN;
 		RETPUSHUNDEF;
 	     }
@@ -859,7 +859,7 @@ PP(pp_tie)
 	     SvTYPE(varsv) == SVt_PVHV))
 	    Perl_croak(aTHX_
 		       "Self-ties of arrays and hashes are not supported");
-	sv_magic(varsv, (SvRV(sv) == varsv ? Nullsv : sv), how, Nullch, 0);
+	sv_magic(varsv, (SvRV(sv) == varsv ? Nullsv : sv), how, NULL, 0);
     }
     LEAVE;
     SP = PL_stack_base + markoff;
@@ -975,7 +975,7 @@ PP(pp_dbmopen)
 
     if (sv_isobject(TOPs)) {
 	sv_unmagic((SV *) hv, PERL_MAGIC_tied);
-	sv_magic((SV*)hv, TOPs, PERL_MAGIC_tied, Nullch, 0);
+	sv_magic((SV*)hv, TOPs, PERL_MAGIC_tied, NULL, 0);
     }
     LEAVE;
     RETURN;
@@ -1172,7 +1172,7 @@ PP(pp_select)
     else {
 	GV * const * const gvp = (GV**)hv_fetch(hv, GvNAME(egv), GvNAMELEN(egv), FALSE);
 	if (gvp && *gvp == egv) {
-	    gv_efullname4(TARG, PL_defoutgv, Nullch, TRUE);
+	    gv_efullname4(TARG, PL_defoutgv, NULL, TRUE);
 	    XPUSHTARG;
 	}
 	else {
@@ -1286,7 +1286,7 @@ PP(pp_enterwrite)
 	if (fgv) {
 	    SV * const tmpsv = sv_newmortal();
 	    const char *name;
-	    gv_efullname4(tmpsv, fgv, Nullch, FALSE);
+	    gv_efullname4(tmpsv, fgv, NULL, FALSE);
 	    name = SvPV_nolen_const(tmpsv);
 	    if (name && *name)
 		DIE(aTHX_ "Undefined format \"%s\" called", name);
@@ -1375,7 +1375,7 @@ PP(pp_leavewrite)
 	if (!cv) {
 	    SV * const sv = sv_newmortal();
 	    const char *name;
-	    gv_efullname4(sv, fgv, Nullch, FALSE);
+	    gv_efullname4(sv, fgv, NULL, FALSE);
 	    name = SvPV_nolen_const(sv);
 	    if (name && *name)
 		DIE(aTHX_ "Undefined top format \"%s\" called",name);
@@ -3218,7 +3218,7 @@ PP(pp_fttext)
 	    (void)PerlIO_close(fp);
 	    RETPUSHUNDEF;
 	}
-	PerlIO_binmode(aTHX_ fp, '<', O_BINARY, Nullch);
+	PerlIO_binmode(aTHX_ fp, '<', O_BINARY, NULL);
 	len = PerlIO_read(fp, tbuf, sizeof(tbuf));
 	(void)PerlIO_close(fp);
 	if (len <= 0) {
@@ -3511,7 +3511,7 @@ S_dooneliner(pTHX_ const char *cmd, const char *filename)
 	/* Need to save/restore 'PL_rs' ?? */
 	s = sv_gets(tmpsv, myfp, 0);
 	(void)PerlProc_pclose(myfp);
-	if (s != Nullch) {
+	if (s != NULL) {
 	    int e;
 	    for (e = 1;
 #ifdef HAS_SYS_ERRLIST
@@ -4753,7 +4753,7 @@ PP(pp_gservent)
 #ifdef HAS_GETSERVBYNAME
 	const char * const proto = POPpbytex;
 	const char * const name = POPpbytex;
-	sent = PerlSock_getservbyname(name, (proto && !*proto) ? Nullch : proto);
+	sent = PerlSock_getservbyname(name, (proto && !*proto) ? NULL : proto);
 #else
 	DIE(aTHX_ PL_no_sock_func, "getservbyname");
 #endif
@@ -4765,7 +4765,7 @@ PP(pp_gservent)
 #ifdef HAS_HTONS
 	port = PerlSock_htons(port);
 #endif
-	sent = PerlSock_getservbyport(port, (proto && !*proto) ? Nullch : proto);
+	sent = PerlSock_getservbyport(port, (proto && !*proto) ? NULL : proto);
 #else
 	DIE(aTHX_ PL_no_sock_func, "getservbyport");
 #endif
diff --git a/regcomp.h b/regcomp.h
index 6a2a22d94e..46a114d002 100644
--- a/regcomp.h
+++ b/regcomp.h
@@ -15,7 +15,7 @@ typedef OP OP_4tree;			/* Will be redefined later. */
  * compile to execute that permits the execute phase to run lots faster on
  * simple cases.  They are:
  *
- * regstart	sv that must begin a match; Nullch if none obvious
+ * regstart	sv that must begin a match; NULL if none obvious
  * reganch	is the match anchored (at beginning-of-line only)?
  * regmust	string (pointer into program) that match must include, or NULL
  *  [regmust changed to SV* for bminstr()--law]
diff --git a/regexec.c b/regexec.c
index fa13a58d8a..66d99bc09c 100644
--- a/regexec.c
+++ b/regexec.c
@@ -405,8 +405,8 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
     char *t;
     const int do_utf8 = sv ? SvUTF8(sv) : 0;	/* if no sv we have to assume bytes */
     I32 ml_anch;
-    register char *other_last = Nullch;	/* other substr checked before this */
-    char *check_at = Nullch;		/* check substr found at this pos */
+    register char *other_last = NULL;	/* other substr checked before this */
+    char *check_at = NULL;		/* check substr found at this pos */
     const I32 multiline = prog->reganch & PMf_MULTILINE;
 #ifdef DEBUGGING
     const char * const i_strpos = strpos;
@@ -957,7 +957,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
   fail:
     DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "%sMatch rejected by optimizer%s\n",
 			  PL_colors[4], PL_colors[5]));
-    return Nullch;
+    return NULL;
 }
 
 /* We know what class REx starts with.  Try to find this position... */
@@ -1992,7 +1992,7 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
 			last = strend - len + 1;
 		    else if (!multiline)
 			last = memEQ(strend - len, little, len)
-			    ? strend - len : Nullch;
+			    ? strend - len : NULL;
 		    else
 			goto find_last;
 		} else {
@@ -2131,7 +2131,7 @@ S_regtry(pTHX_ regexp *prog, char *startpos)
 		  && (mg = mg_find(PL_reg_sv, PERL_MAGIC_regex_global)))) {
 		/* prepare for quick setting of pos */
 		sv_magic(PL_reg_sv, (SV*)0,
-			PERL_MAGIC_regex_global, Nullch, 0);
+			PERL_MAGIC_regex_global, NULL, 0);
 		mg = mg_find(PL_reg_sv, PERL_MAGIC_regex_global);
 		mg->mg_len = -1;
 	    }
@@ -2167,7 +2167,7 @@ S_regtry(pTHX_ regexp *prog, char *startpos)
 	    RX_MATCH_COPIED_off(prog);
 	}
 	else
-	    PL_reg_oldsaved = Nullch;
+	    PL_reg_oldsaved = NULL;
 	prog->subbeg = PL_bostr;
 	prog->sublen = PL_regeol - PL_bostr; /* strend may have been modified */
     }
@@ -2385,7 +2385,7 @@ S_regmatch(pTHX_ regnode *prog)
 				   function of same name */
     register I32 n;		/* no or next */
     register I32 ln = 0;	/* len or last */
-    register char *s = Nullch;	/* operand or save */
+    register char *s = NULL;	/* operand or save */
     register char *locinput = PL_reginput;
     register I32 c1 = 0, c2 = 0, paren;	/* case fold search, parenth */
     int minmod = 0, sw = 0, logical = 0;
@@ -4600,7 +4600,7 @@ STATIC I32
 S_regrepeat_hard(pTHX_ regnode *p, I32 max, I32 *lp)
 {
     dVAR;
-    register char *scan = Nullch;
+    register char *scan = NULL;
     register char *start;
     register char *loceol = PL_regeol;
     I32 l = 0;
diff --git a/sv.c b/sv.c
index df47226eba..8778904e81 100644
--- a/sv.c
+++ b/sv.c
@@ -242,7 +242,7 @@ S_more_sv(pTHX)
 
     if (PL_nice_chunk) {
 	sv_add_arena(PL_nice_chunk, PL_nice_chunk_size, 0);
-	PL_nice_chunk = Nullch;
+	PL_nice_chunk = NULL;
         PL_nice_chunk_size = 0;
     }
     else {
@@ -599,7 +599,7 @@ Perl_sv_free_arenas(pTHX)
 	PL_body_roots[i] = 0;
 
     Safefree(PL_nice_chunk);
-    PL_nice_chunk = Nullch;
+    PL_nice_chunk = NULL;
     PL_nice_chunk_size = 0;
     PL_sv_arenaroot = 0;
     PL_sv_root = 0;
@@ -2925,7 +2925,7 @@ S_glob_assign(pTHX_ SV *dstr, SV *sstr, const int dtype)
 	/* don't upgrade SVt_PVLV: it can hold a glob */
 	if (dtype != SVt_PVLV)
 	    sv_upgrade(dstr, SVt_PVGV);
-	sv_magic(dstr, dstr, PERL_MAGIC_glob, Nullch, 0);
+	sv_magic(dstr, dstr, PERL_MAGIC_glob, NULL, 0);
 	GvSTASH(dstr) = GvSTASH(sstr);
 	if (GvSTASH(dstr))
 	    Perl_sv_add_backref(aTHX_ (SV*)GvSTASH(dstr), dstr);
@@ -3042,7 +3042,7 @@ S_pvgv_assign(pTHX_ SV *dstr, SV *sstr) {
 		    }
 		if (!intro)
 		    cv_ckproto(cv, (GV*)dstr,
-			       SvPOK(sref) ? SvPVX_const(sref) : Nullch);
+			       SvPOK(sref) ? SvPVX_const(sref) : NULL);
 	    }
 	    GvCV(dstr) = (CV*)sref;
 	    GvCVGEN(dstr) = 0; /* Switch off cacheness. */
@@ -3780,7 +3780,7 @@ Perl_sv_force_normal_flags(pTHX_ register SV *sv, U32 flags)
 	    const STRLEN len = SvCUR(sv);
 	    SvFAKE_off(sv);
 	    SvREADONLY_off(sv);
-	    SvPV_set(sv, Nullch);
+	    SvPV_set(sv, NULL);
 	    SvLEN_set(sv, 0);
 	    SvGROW(sv, len + 1);
 	    Move(pvx,SvPVX(sv),len,char);
@@ -5416,7 +5416,7 @@ Perl_sv_eq(pTHX_ register SV *sv1, register SV *sv2)
     const char *pv2;
     STRLEN cur2;
     I32  eq     = 0;
-    char *tpv   = Nullch;
+    char *tpv   = NULL;
     SV* svrecode = Nullsv;
 
     if (!sv1) {
@@ -5509,7 +5509,7 @@ Perl_sv_cmp(pTHX_ register SV *sv1, register SV *sv2)
     dVAR;
     STRLEN cur1, cur2;
     const char *pv1, *pv2;
-    char *tpv = Nullch;
+    char *tpv = NULL;
     I32  cmp;
     SV *svrecode = Nullsv;
 
@@ -6053,7 +6053,7 @@ screamer2:
     }
 
 return_string_or_null:
-    return (SvCUR(sv) - append) ? SvPVX(sv) : Nullch;
+    return (SvCUR(sv) - append) ? SvPVX(sv) : NULL;
 }
 
 /*
@@ -6791,7 +6791,7 @@ Perl_sv_reset(pTHX_ register const char *s, HV *stash)
 		    SvOK_off(sv);
 		    if (SvTYPE(sv) >= SVt_PV) {
 			SvCUR_set(sv, 0);
-			if (SvPVX_const(sv) != Nullch)
+			if (SvPVX_const(sv) != NULL)
 			    *SvPVX(sv) = '\0';
 			SvTAINT(sv);
 		    }
@@ -6931,7 +6931,7 @@ Perl_sv_2cv(pTHX_ SV *sv, HV **st, GV **gvp, I32 lref)
 	    SV *tmpsv;
 	    ENTER;
 	    tmpsv = newSV(0);
-	    gv_efullname3(tmpsv, gv, Nullch);
+	    gv_efullname3(tmpsv, gv, NULL);
 	    /* XXX this is probably not what they think they're getting.
 	     * It has the same effect as "sub name;", i.e. just a forward
 	     * declaration! */
@@ -7246,7 +7246,7 @@ Copies a pointer into a new SV, optionally blessing the SV.  The C<rv>
 argument will be upgraded to an RV.  That RV will be modified to point to
 the new SV.  If the C<pv> argument is NULL then C<PL_sv_undef> will be placed
 into the SV.  The C<classname> argument indicates the package for the
-blessing.  Set C<classname> to C<Nullch> to avoid the blessing.  The new SV
+blessing.  Set C<classname> to C<NULL> to avoid the blessing.  The new SV
 will have a reference count of 1, and the RV will be returned.
 
 Do not use with other Perl types such as HV, AV, SV, CV, because those
@@ -7276,7 +7276,7 @@ Perl_sv_setref_pv(pTHX_ SV *rv, const char *classname, void *pv)
 Copies an integer into a new SV, optionally blessing the SV.  The C<rv>
 argument will be upgraded to an RV.  That RV will be modified to point to
 the new SV.  The C<classname> argument indicates the package for the
-blessing.  Set C<classname> to C<Nullch> to avoid the blessing.  The new SV
+blessing.  Set C<classname> to C<NULL> to avoid the blessing.  The new SV
 will have a reference count of 1, and the RV will be returned.
 
 =cut
@@ -7295,7 +7295,7 @@ Perl_sv_setref_iv(pTHX_ SV *rv, const char *classname, IV iv)
 Copies an unsigned integer into a new SV, optionally blessing the SV.  The C<rv>
 argument will be upgraded to an RV.  That RV will be modified to point to
 the new SV.  The C<classname> argument indicates the package for the
-blessing.  Set C<classname> to C<Nullch> to avoid the blessing.  The new SV
+blessing.  Set C<classname> to C<NULL> to avoid the blessing.  The new SV
 will have a reference count of 1, and the RV will be returned.
 
 =cut
@@ -7314,7 +7314,7 @@ Perl_sv_setref_uv(pTHX_ SV *rv, const char *classname, UV uv)
 Copies a double into a new SV, optionally blessing the SV.  The C<rv>
 argument will be upgraded to an RV.  That RV will be modified to point to
 the new SV.  The C<classname> argument indicates the package for the
-blessing.  Set C<classname> to C<Nullch> to avoid the blessing.  The new SV
+blessing.  Set C<classname> to C<NULL> to avoid the blessing.  The new SV
 will have a reference count of 1, and the RV will be returned.
 
 =cut
@@ -7334,7 +7334,7 @@ Copies a string into a new SV, optionally blessing the SV.  The length of the
 string must be specified with C<n>.  The C<rv> argument will be upgraded to
 an RV.  That RV will be modified to point to the new SV.  The C<classname>
 argument indicates the package for the blessing.  Set C<classname> to
-C<Nullch> to avoid the blessing.  The new SV will have a reference count
+C<NULL> to avoid the blessing.  The new SV will have a reference count
 of 1, and the RV will be returned.
 
 Note that C<sv_setref_pv> copies the pointer while this copies the string.
@@ -7800,7 +7800,7 @@ S_F0convert(NV nv, char *endbuf, STRLEN *len)
 	*len = endbuf - p;
 	return p;
     }
-    return Nullch;
+    return NULL;
 }
 
 
@@ -7940,7 +7940,7 @@ Perl_sv_vcatpvfn(pTHX_ SV *sv, const char *pat, STRLEN patlen, va_list *args, SV
 	U8 utf8buf[UTF8_MAXBYTES+1];
 	STRLEN esignlen = 0;
 
-	const char *eptr = Nullch;
+	const char *eptr = NULL;
 	STRLEN elen = 0;
 	SV *vecsv = Nullsv;
 	const U8 *vecstr = Null(U8*);
@@ -9030,7 +9030,7 @@ Perl_re_dup(pTHX_ const REGEXP *r, CLONE_PARAMS *param)
     if (RX_MATCH_COPIED(ret))
 	ret->subbeg  = SAVEPVN(r->subbeg, r->sublen);
     else
-	ret->subbeg = Nullch;
+	ret->subbeg = NULL;
 #ifdef PERL_OLD_COPY_ON_WRITE
     ret->saved_copy = Nullsv;
 #endif
@@ -9572,7 +9572,7 @@ Perl_sv_dup(pTHX_ const SV *sstr, CLONE_PARAMS* param)
 		    }
 		}
 		else {
-		    SvPV_set(dstr, Nullch);
+		    SvPV_set(dstr, NULL);
 		    AvALLOC((AV*)dstr)	= (SV**)NULL;
 		}
 		break;
@@ -9620,7 +9620,7 @@ Perl_sv_dup(pTHX_ const SV *sstr, CLONE_PARAMS* param)
 			}
 		    }
 		    else {
-			SvPV_set(dstr, Nullch);
+			SvPV_set(dstr, NULL);
 		    }
 		    /* Record stashes for possible cloning in Perl_clone(). */
 		    if(hvname)
@@ -10492,7 +10492,7 @@ perl_clone_using(PerlInterpreter *proto_perl, UV flags,
     if (proto_perl->Iop_mask)
 	PL_op_mask	= SAVEPVN(proto_perl->Iop_mask, PL_maxo);
     else
-	PL_op_mask 	= Nullch;
+	PL_op_mask 	= NULL;
     /* PL_asserting        = proto_perl->Iasserting; */
 
     /* current interpreter roots */
@@ -10510,7 +10510,7 @@ perl_clone_using(PerlInterpreter *proto_perl, UV flags,
     PL_lastfd		= proto_perl->Ilastfd;
     PL_oldname		= proto_perl->Ioldname;		/* XXX not quite right */
     PL_Argv		= NULL;
-    PL_Cmd		= Nullch;
+    PL_Cmd		= NULL;
     PL_gensym		= proto_perl->Igensym;
     PL_preambled	= proto_perl->Ipreambled;
     PL_preambleav	= av_dup_inc(proto_perl->Ipreambleav, param);
@@ -10747,7 +10747,7 @@ perl_clone_using(PerlInterpreter *proto_perl, UV flags,
     PL_glob_index	= proto_perl->Iglob_index;
     PL_srand_called	= proto_perl->Isrand_called;
     PL_uudmap['M']	= 0;		/* reinits on demand */
-    PL_bitcount		= Nullch;	/* reinits on demand */
+    PL_bitcount		= NULL;	/* reinits on demand */
 
     if (proto_perl->Ipsig_pend) {
 	Newxz(PL_psig_pend, SIG_SIZE, int);
@@ -10883,7 +10883,7 @@ perl_clone_using(PerlInterpreter *proto_perl, UV flags,
     PL_sortstash	= hv_dup(proto_perl->Tsortstash, param);
     PL_firstgv		= gv_dup(proto_perl->Tfirstgv, param);
     PL_secondgv		= gv_dup(proto_perl->Tsecondgv, param);
-    PL_efloatbuf	= Nullch;		/* reinits on demand */
+    PL_efloatbuf	= NULL;		/* reinits on demand */
     PL_efloatsize	= 0;			/* reinits on demand */
 
     /* regex stuff */
@@ -10894,26 +10894,26 @@ perl_clone_using(PerlInterpreter *proto_perl, UV flags,
     PL_lastscream	= Nullsv;
 
     PL_watchaddr	= NULL;
-    PL_watchok		= Nullch;
+    PL_watchok		= NULL;
 
     PL_regdummy		= proto_perl->Tregdummy;
-    PL_regprecomp	= Nullch;
+    PL_regprecomp	= NULL;
     PL_regnpar		= 0;
     PL_regsize		= 0;
     PL_colorset		= 0;		/* reinits PL_colors[] */
     /*PL_colors[6]	= {0,0,0,0,0,0};*/
-    PL_reginput		= Nullch;
-    PL_regbol		= Nullch;
-    PL_regeol		= Nullch;
+    PL_reginput		= NULL;
+    PL_regbol		= NULL;
+    PL_regeol		= NULL;
     PL_regstartp	= (I32*)NULL;
     PL_regendp		= (I32*)NULL;
     PL_reglastparen	= (U32*)NULL;
     PL_reglastcloseparen	= (U32*)NULL;
-    PL_regtill		= Nullch;
+    PL_regtill		= NULL;
     PL_reg_start_tmp	= (char**)NULL;
     PL_reg_start_tmpl	= 0;
     PL_regdata		= (struct reg_data*)NULL;
-    PL_bostr		= Nullch;
+    PL_bostr		= NULL;
     PL_reg_flags	= 0;
     PL_reg_eval_set	= 0;
     PL_regnarrate	= 0;
@@ -10922,21 +10922,21 @@ perl_clone_using(PerlInterpreter *proto_perl, UV flags,
     PL_regcc		= (CURCUR*)NULL;
     PL_reg_call_cc	= (struct re_cc_state*)NULL;
     PL_reg_re		= (regexp*)NULL;
-    PL_reg_ganch	= Nullch;
+    PL_reg_ganch	= NULL;
     PL_reg_sv		= Nullsv;
     PL_reg_match_utf8	= FALSE;
     PL_reg_magic	= (MAGIC*)NULL;
     PL_reg_oldpos	= 0;
     PL_reg_oldcurpm	= (PMOP*)NULL;
     PL_reg_curpm	= (PMOP*)NULL;
-    PL_reg_oldsaved	= Nullch;
+    PL_reg_oldsaved	= NULL;
     PL_reg_oldsavedlen	= 0;
 #ifdef PERL_OLD_COPY_ON_WRITE
     PL_nrs		= Nullsv;
 #endif
     PL_reg_maxiter	= 0;
     PL_reg_leftiter	= 0;
-    PL_reg_poscache	= Nullch;
+    PL_reg_poscache	= NULL;
     PL_reg_poscache_size= 0;
 
     /* RE engine - function pointers */
diff --git a/sv.h b/sv.h
index d8597ad001..f72db8409d 100644
--- a/sv.h
+++ b/sv.h
@@ -1054,7 +1054,7 @@ Taints an SV if tainting is enabled.
 =cut
 */
 
-#define sv_taint(sv)	  sv_magic((sv), Nullsv, PERL_MAGIC_taint, Nullch, 0)
+#define sv_taint(sv)	  sv_magic((sv), Nullsv, PERL_MAGIC_taint, NULL, 0)
 
 #define SvTAINTED(sv)	  (SvMAGICAL(sv) && sv_tainted(sv))
 #define SvTAINTED_on(sv)  STMT_START{ if(PL_tainting){sv_taint(sv);}   }STMT_END
diff --git a/thrdvar.h b/thrdvar.h
index e12e85f317..18c426ce2e 100644
--- a/thrdvar.h
+++ b/thrdvar.h
@@ -196,7 +196,7 @@ PERLVAR(Treg_oldsaved,	char*)		/* old saved substr during match */
 PERLVAR(Treg_oldsavedlen, STRLEN)	/* old length of saved substr during match */
 PERLVAR(Treg_maxiter,	I32)		/* max wait until caching pos */
 PERLVAR(Treg_leftiter,	I32)		/* wait until caching pos */
-PERLVARI(Treg_poscache, char *, Nullch)	/* cache of pos of WHILEM */
+PERLVARI(Treg_poscache, char *, NULL)	/* cache of pos of WHILEM */
 PERLVAR(Treg_poscache_size, STRLEN)	/* size of pos cache of WHILEM */
 
 PERLVARI(Tpeepp,	peep_t, MEMBER_TO_FPTR(Perl_peep))
diff --git a/toke.c b/toke.c
index 95f86fa372..db51dbcbec 100644
--- a/toke.c
+++ b/toke.c
@@ -288,7 +288,7 @@ S_tokereport(pTHX_ I32 rv)
 {
     dVAR;
     if (DEBUG_T_TEST) {
-	const char *name = Nullch;
+	const char *name = NULL;
 	enum token_type type = TOKENTYPE_NONE;
 	const struct debug_tokens *p;
 	SV* const report = newSVpvs("<== ");
@@ -623,7 +623,7 @@ Perl_lex_start(pTHX_ SV *line)
     SvTEMP_off(PL_linestr);
     PL_oldoldbufptr = PL_oldbufptr = PL_bufptr = PL_linestart = SvPVX(PL_linestr);
     PL_bufend = PL_bufptr + SvCUR(PL_linestr);
-    PL_last_lop = PL_last_uni = Nullch;
+    PL_last_lop = PL_last_uni = NULL;
     PL_rsfp = 0;
 }
 
@@ -786,7 +786,7 @@ S_skipspace(pTHX_ register char *s)
 
 	/* try to recharge the buffer */
 	if ((s = filter_gets(PL_linestr, PL_rsfp,
-			     (prevlen = SvCUR(PL_linestr)))) == Nullch)
+			     (prevlen = SvCUR(PL_linestr)))) == NULL)
 	{
 	    /* end of file.  Add on the -p or -n magic */
 	    if (PL_minus_p) {
@@ -805,7 +805,7 @@ S_skipspace(pTHX_ register char *s)
 	    PL_oldoldbufptr = PL_oldbufptr = PL_bufptr = s = PL_linestart
 		= SvPVX(PL_linestr);
 	    PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
-	    PL_last_lop = PL_last_uni = Nullch;
+	    PL_last_lop = PL_last_uni = NULL;
 
 	    /* Close the filehandle.  Could be from -P preprocessor,
 	     * STDIN, or a regular file.  If we were reading code from
@@ -1285,7 +1285,7 @@ S_sublex_push(pTHX)
     PL_bufend = PL_bufptr = PL_oldbufptr = PL_oldoldbufptr = PL_linestart
 	= SvPVX(PL_linestr);
     PL_bufend += SvCUR(PL_linestr);
-    PL_last_lop = PL_last_uni = Nullch;
+    PL_last_lop = PL_last_uni = NULL;
     SAVEFREESV(PL_linestr);
 
     PL_lex_dojoin = FALSE;
@@ -1336,7 +1336,7 @@ S_sublex_done(pTHX)
 	PL_lex_inpat = 0;
 	PL_bufend = PL_bufptr = PL_oldbufptr = PL_oldoldbufptr = PL_linestart = SvPVX(PL_linestr);
 	PL_bufend += SvCUR(PL_linestr);
-	PL_last_lop = PL_last_uni = Nullch;
+	PL_last_lop = PL_last_uni = NULL;
 	SAVEFREESV(PL_linestr);
 	PL_lex_dojoin = FALSE;
 	PL_lex_brackets = 0;
@@ -1788,7 +1788,7 @@ S_scan_const(pTHX_ char *start)
 			goto NUM_ESCAPE_INSERT;
 		    }
 		    res = newSVpvn(s + 1, e - s - 1);
-		    res = new_constant( Nullch, 0, "charnames",
+		    res = new_constant( NULL, 0, "charnames",
 					res, Nullsv, "\\N{...}" );
 		    if (has_utf8)
 			sv_utf8_upgrade(res);
@@ -2356,7 +2356,7 @@ S_filter_gets(pTHX_ register SV *sv, register PerlIO *fp, STRLEN append)
         if (FILTER_READ(0, sv, 0) > 0)
             return ( SvPVX(sv) ) ;
         else
-	    return Nullch ;
+	    return NULL ;
     }
     else
         return (sv_gets(sv, fp, append));
@@ -2758,7 +2758,7 @@ Perl_yylex(pTHX)
 	    sv_catpvs(PL_linestr, "\n");
 	    PL_oldoldbufptr = PL_oldbufptr = s = PL_linestart = SvPVX(PL_linestr);
 	    PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
-	    PL_last_lop = PL_last_uni = Nullch;
+	    PL_last_lop = PL_last_uni = NULL;
 	    if (PERLDB_LINE && PL_curstash != PL_debstash) {
 		SV * const sv = newSV(0);
 
@@ -2772,7 +2772,7 @@ Perl_yylex(pTHX)
 	}
 	do {
 	    bof = PL_rsfp ? TRUE : FALSE;
-	    if ((s = filter_gets(PL_linestr, PL_rsfp, 0)) == Nullch) {
+	    if ((s = filter_gets(PL_linestr, PL_rsfp, 0)) == NULL) {
 	      fake_eof:
 		if (PL_rsfp) {
 		    if (PL_preprocess && !PL_in_eval)
@@ -2789,12 +2789,12 @@ Perl_yylex(pTHX)
 			     ? ";}continue{print;}" : ";}");
 		    PL_oldoldbufptr = PL_oldbufptr = s = PL_linestart = SvPVX(PL_linestr);
 		    PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
-		    PL_last_lop = PL_last_uni = Nullch;
+		    PL_last_lop = PL_last_uni = NULL;
 		    PL_minus_n = PL_minus_p = 0;
 		    goto retry;
 		}
 		PL_oldoldbufptr = PL_oldbufptr = s = PL_linestart = SvPVX(PL_linestr);
-		PL_last_lop = PL_last_uni = Nullch;
+		PL_last_lop = PL_last_uni = NULL;
 		sv_setpvn(PL_linestr,"",0);
 		TOKEN(';');	/* not infinite loop because rsfp is NULL now */
 	    }
@@ -2839,7 +2839,7 @@ Perl_yylex(pTHX)
 		    sv_setpvn(PL_linestr, "", 0);
 		    PL_oldoldbufptr = PL_oldbufptr = s = PL_linestart = SvPVX(PL_linestr);
 		    PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
-		    PL_last_lop = PL_last_uni = Nullch;
+		    PL_last_lop = PL_last_uni = NULL;
 		    PL_doextract = FALSE;
 		}
 	    }
@@ -2856,13 +2856,13 @@ Perl_yylex(pTHX)
 	    av_store(CopFILEAVx(PL_curcop),(I32)CopLINE(PL_curcop),sv);
 	}
 	PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
-	PL_last_lop = PL_last_uni = Nullch;
+	PL_last_lop = PL_last_uni = NULL;
 	if (CopLINE(PL_curcop) == 1) {
 	    while (s < PL_bufend && isSPACE(*s))
 		s++;
 	    if (*s == ':' && s[1] != ':') /* for csh execing sh scripts */
 		s++;
-	    d = Nullch;
+	    d = NULL;
 	    if (!PL_in_eval) {
 		if (*s == '#' && *(s+1) == '!')
 		    d = s + 2;
@@ -2935,7 +2935,7 @@ Perl_yylex(pTHX)
 			    }
 			}
 			if (d < ipath)
-			    d = Nullch;
+			    d = NULL;
 		    }
 #endif
 		}
@@ -2954,7 +2954,7 @@ Perl_yylex(pTHX)
 		    while (*c && !strchr("; \t\r\n\f\v#", *c))
 			c++;
 		    if (c < d)
-			d = Nullch;	/* "perl" not in first word; ignore */
+			d = NULL;	/* "perl" not in first word; ignore */
 		    else
 			*s = '#';	/* Don't try to parse shebang line */
 		}
@@ -3026,7 +3026,7 @@ Perl_yylex(pTHX)
 			    sv_setpvn(PL_linestr, "", 0);
 			    PL_oldoldbufptr = PL_oldbufptr = s = PL_linestart = SvPVX(PL_linestr);
 			    PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
-			    PL_last_lop = PL_last_uni = Nullch;
+			    PL_last_lop = PL_last_uni = NULL;
 			    PL_preambled = FALSE;
 			    if (PERLDB_LINE)
 				(void)gv_fetchfile(PL_origfilename);
@@ -9869,7 +9869,7 @@ S_scan_heredoc(pTHX_ register char *s)
 	sv_setsv(PL_linestr,herewas);
 	PL_oldoldbufptr = PL_oldbufptr = PL_bufptr = s = PL_linestart = SvPVX(PL_linestr);
 	PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
-	PL_last_lop = PL_last_uni = Nullch;
+	PL_last_lop = PL_last_uni = NULL;
     }
     else
 	sv_setpvn(tmpstr,"",0);   /* avoid "uninitialized" warning */
@@ -9881,7 +9881,7 @@ S_scan_heredoc(pTHX_ register char *s)
 	}
 	CopLINE_inc(PL_curcop);
 	PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
-	PL_last_lop = PL_last_uni = Nullch;
+	PL_last_lop = PL_last_uni = NULL;
 #ifndef PERL_STRICT_CR
 	if (PL_bufend - PL_linestart >= 2) {
 	    if ((PL_bufend[-2] == '\r' && PL_bufend[-1] == '\n') ||
@@ -10366,7 +10366,7 @@ S_scan_str(pTHX_ char *start, int keep_quoted, int keep_delims)
 	 !(PL_oldoldbufptr = PL_oldbufptr = s = PL_linestart = filter_gets(PL_linestr, PL_rsfp, 0))) {
 	    sv_free(sv);
 	    CopLINE_set(PL_curcop, (line_t)PL_multi_start);
-	    return Nullch;
+	    return NULL;
 	}
 	/* we read a line, so increment our line counter */
 	CopLINE_inc(PL_curcop);
@@ -10384,7 +10384,7 @@ S_scan_str(pTHX_ char *start, int keep_quoted, int keep_delims)
 
 	/* having changed the buffer, we must update PL_bufend */
 	PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
-	PL_last_lop = PL_last_uni = Nullch;
+	PL_last_lop = PL_last_uni = NULL;
     }
 
     /* at this point, we have successfully read the delimited string */
@@ -10877,7 +10877,7 @@ S_scan_formline(pTHX_ register char *s)
 	    s = filter_gets(PL_linestr, PL_rsfp, 0);
 	    PL_oldoldbufptr = PL_oldbufptr = PL_bufptr = PL_linestart = SvPVX(PL_linestr);
 	    PL_bufend = PL_bufptr + SvCUR(PL_linestr);
-	    PL_last_lop = PL_last_uni = Nullch;
+	    PL_last_lop = PL_last_uni = NULL;
 	    if (!s) {
 		s = PL_bufptr;
 		break;
diff --git a/util.c b/util.c
index 636b06d922..b70d3154a4 100644
--- a/util.c
+++ b/util.c
@@ -92,7 +92,7 @@ Perl_safesysmalloc(MEM_SIZE size)
     ptr = (Malloc_t)PerlMem_malloc(size?size:1);	/* malloc(0) is NASTY on our system */
     PERL_ALLOC_CHECK(ptr);
     DEBUG_m(PerlIO_printf(Perl_debug_log, "0x%"UVxf": (%05ld) malloc %ld bytes\n",PTR2UV(ptr),(long)PL_an++,(long)size));
-    if (ptr != Nullch) {
+    if (ptr != NULL) {
 #ifdef PERL_TRACK_MEMPOOL
         ((struct perl_memory_debug_header *)ptr)->interpreter = aTHX;
 #  ifdef PERL_POISON
@@ -104,7 +104,7 @@ Perl_safesysmalloc(MEM_SIZE size)
 	return ptr;
 }
     else if (PL_nomemok)
-	return Nullch;
+	return NULL;
     else {
 	return write_no_mem();
     }
@@ -162,14 +162,14 @@ Perl_safesysrealloc(Malloc_t where,MEM_SIZE size)
     DEBUG_m(PerlIO_printf(Perl_debug_log, "0x%"UVxf": (%05ld) rfree\n",PTR2UV(where),(long)PL_an++));
     DEBUG_m(PerlIO_printf(Perl_debug_log, "0x%"UVxf": (%05ld) realloc %ld bytes\n",PTR2UV(ptr),(long)PL_an++,(long)size));
 
-    if (ptr != Nullch) {
+    if (ptr != NULL) {
 #ifdef PERL_TRACK_MEMPOOL
         ptr = (Malloc_t)((char*)ptr+sTHX);
 #endif
 	return ptr;
     }
     else if (PL_nomemok)
-	return Nullch;
+	return NULL;
     else {
 	return write_no_mem();
     }
@@ -239,7 +239,7 @@ Perl_safesyscalloc(MEM_SIZE count, MEM_SIZE size)
     ptr = (Malloc_t)PerlMem_malloc(size?size:1);	/* malloc(0) is NASTY on our system */
     PERL_ALLOC_CHECK(ptr);
     DEBUG_m(PerlIO_printf(Perl_debug_log, "0x%"UVxf": (%05ld) calloc %ld x %ld bytes\n",PTR2UV(ptr),(long)PL_an++,(long)count,(long)size));
-    if (ptr != Nullch) {
+    if (ptr != NULL) {
 	memset((void*)ptr, 0, size);
 #ifdef PERL_TRACK_MEMPOOL
         ((struct perl_memory_debug_header *)ptr)->interpreter = aTHX;
@@ -252,7 +252,7 @@ Perl_safesyscalloc(MEM_SIZE count, MEM_SIZE size)
 	return ptr;
     }
     else if (PL_nomemok)
-	return Nullch;
+	return NULL;
     return write_no_mem();
 }
 
@@ -334,7 +334,7 @@ Perl_instr(pTHX_ register const char *big, register const char *little)
 	    continue;
 	for (x=big,s=little; *s; /**/ ) {
 	    if (!*x)
-		return Nullch;
+		return NULL;
 	    if (*s != *x)
 		break;
 	    else {
@@ -345,7 +345,7 @@ Perl_instr(pTHX_ register const char *big, register const char *little)
 	if (!*s)
 	    return (char*)(big-1);
     }
-    return Nullch;
+    return NULL;
 }
 
 /* same as instr but allow embedded nulls */
@@ -370,7 +370,7 @@ Perl_ninstr(pTHX_ const char *big, const char *bigend, const char *little, const
             return (char*)(big-1);
         }
     }
-    return Nullch;
+    return NULL;
 }
 
 /* reverse of the above--find last substring */
@@ -401,7 +401,7 @@ Perl_rninstr(pTHX_ register const char *big, const char *bigend, const char *lit
 	if (s >= littleend)
 	    return (char*)(big+1);
     }
-    return Nullch;
+    return NULL;
 }
 
 #define FBM_TABLE_OFFSET 2	/* Number of bytes between EOS and table*/
@@ -461,7 +461,7 @@ Perl_fbm_compile(pTHX_ SV *sv, U32 flags)
 	    s--, i++;
 	}
     }
-    sv_magic(sv, Nullsv, PERL_MAGIC_bm, Nullch, 0);	/* deep magic */
+    sv_magic(sv, Nullsv, PERL_MAGIC_bm, NULL, 0);	/* deep magic */
     SvVALID_on(sv);
 
     s = (const unsigned char*)(SvPVX_const(sv));	/* deeper magic */
@@ -488,7 +488,7 @@ Perl_fbm_compile(pTHX_ SV *sv, U32 flags)
 =for apidoc fbm_instr
 
 Returns the location of the SV in the string delimited by C<str> and
-C<strend>.  It returns C<Nullch> if the string can't be found.  The C<sv>
+C<strend>.  It returns C<NULL> if the string can't be found.  The C<sv>
 does not have to be fbm_compiled, but the search will not be as fast
 then.
 
@@ -512,7 +512,7 @@ Perl_fbm_instr(pTHX_ unsigned char *big, register unsigned char *bigend, SV *lit
 		 || (*big == *little &&
 		     memEQ((char *)big, (char *)little, littlelen - 1))))
 	    return (char*)big;
-	return Nullch;
+	return NULL;
     }
 
     if (littlelen <= 2) {		/* Special-cased */
@@ -532,7 +532,7 @@ Perl_fbm_instr(pTHX_ unsigned char *big, register unsigned char *bigend, SV *lit
 	    }
 	    if (SvTAIL(littlestr))
 		return (char *) bigend;
-	    return Nullch;
+	    return NULL;
 	}
 	if (!littlelen)
 	    return (char*)big;		/* Cannot be SvTAIL! */
@@ -543,7 +543,7 @@ Perl_fbm_instr(pTHX_ unsigned char *big, register unsigned char *bigend, SV *lit
 		return (char*)bigend - 2;
 	    if (bigend[-1] == *little)
 		return (char*)bigend - 1;
-	    return Nullch;
+	    return NULL;
 	}
 	{
 	    /* This should be better than FBM if c1 == c2, and almost
@@ -596,7 +596,7 @@ Perl_fbm_instr(pTHX_ unsigned char *big, register unsigned char *bigend, SV *lit
       check_1char_anchor:		/* One char and anchor! */
 	if (SvTAIL(littlestr) && (*bigend == *little))
 	    return (char *)bigend;	/* bigend is already decremented. */
-	return Nullch;
+	return NULL;
     }
     if (SvTAIL(littlestr) && !multiline) {	/* tail anchored? */
 	s = bigend - littlelen;
@@ -611,7 +611,7 @@ Perl_fbm_instr(pTHX_ unsigned char *big, register unsigned char *bigend, SV *lit
 	{
 	    return (char*)s + 1;	/* how sweet it is */
 	}
-	return Nullch;
+	return NULL;
     }
     if (SvTYPE(littlestr) != SVt_PVBM || !SvVALID(littlestr)) {
 	char * const b = ninstr((char*)big,(char*)bigend,
@@ -625,7 +625,7 @@ Perl_fbm_instr(pTHX_ unsigned char *big, register unsigned char *bigend, SV *lit
 	    {
 		return (char*)s;
 	    }
-	    return Nullch;
+	    return NULL;
 	}
 	return b;
     }
@@ -635,7 +635,7 @@ Perl_fbm_instr(pTHX_ unsigned char *big, register unsigned char *bigend, SV *lit
 	register const unsigned char *oldlittle;
 
 	if (littlelen > (STRLEN)(bigend - big))
-	    return Nullch;
+	    return NULL;
 	--littlelen;			/* Last char found by table lookup */
 
 	s = big + littlelen;
@@ -672,7 +672,7 @@ Perl_fbm_instr(pTHX_ unsigned char *big, register unsigned char *bigend, SV *lit
 	     && memEQ((char *)(bigend - littlelen),
 		      (char *)(oldlittle - littlelen), littlelen) )
 	    return (char*)bigend - littlelen;
-	return Nullch;
+	return NULL;
     }
 }
 
@@ -715,7 +715,7 @@ Perl_screaminstr(pTHX_ SV *bigstr, SV *littlestr, I32 start_shift, I32 end_shift
 	    first = *little++;
 	    goto check_tail;
 	}
-	return Nullch;
+	return NULL;
     }
 
     little = (const unsigned char *)(SvPVX_const(littlestr));
@@ -735,7 +735,7 @@ Perl_screaminstr(pTHX_ SV *bigstr, SV *littlestr, I32 start_shift, I32 end_shift
 	if (previous + start_shift == stop_pos + 1) /* A fake '\n'? */
 	    goto check_tail;
 #endif
-	return Nullch;
+	return NULL;
     }
     while (pos < previous + start_shift) {
 	if (!(pos += PL_screamnext[pos]))
@@ -763,7 +763,7 @@ Perl_screaminstr(pTHX_ SV *bigstr, SV *littlestr, I32 start_shift, I32 end_shift
 	return (char *)(big+(*old_posp));
   check_tail:
     if (!SvTAIL(littlestr) || (end_shift > 0))
-	return Nullch;
+	return NULL;
     /* Ignore the trailing "\n".  This code is not microoptimized */
     big = (const unsigned char *)(SvPVX_const(bigstr) + SvCUR(bigstr));
     stop_pos = littleend - little;	/* Actual littlestr len */
@@ -774,7 +774,7 @@ Perl_screaminstr(pTHX_ SV *bigstr, SV *littlestr, I32 start_shift, I32 end_shift
 	&& ((stop_pos == 1) ||
 	    memEQ((char *)(big + 1), (char *)little, stop_pos - 1)))
 	return (char*)big;
-    return Nullch;
+    return NULL;
 }
 
 I32
@@ -823,7 +823,7 @@ char *
 Perl_savepv(pTHX_ const char *pv)
 {
     if (!pv)
-	return Nullch;
+	return NULL;
     else {
 	char *newaddr;
 	const STRLEN pvlen = strlen(pv)+1;
@@ -877,7 +877,7 @@ Perl_savesharedpv(pTHX_ const char *pv)
     register char *newaddr;
     STRLEN pvlen;
     if (!pv)
-	return Nullch;
+	return NULL;
 
     pvlen = strlen(pv)+1;
     newaddr = (char*)PerlMemShared_malloc(pvlen);
@@ -1201,7 +1201,7 @@ S_vdie_croak_common(pTHX_ const char* pat, va_list* args, STRLEN* msglen,
 	*utf8 = SvUTF8(msv);
     }
     else {
-	message = Nullch;
+	message = NULL;
     }
 
     DEBUG_S(PerlIO_printf(Perl_debug_log,
@@ -1309,11 +1309,11 @@ function.  Calling C<croak> returns control directly to Perl,
 sidestepping the normal C order of execution. See C<warn>.
 
 If you want to throw an exception object, assign the object to
-C<$@> and then pass C<Nullch> to croak():
+C<$@> and then pass C<NULL> to croak():
 
    errsv = get_sv("@", TRUE);
    sv_setsv(errsv, exception_object);
-   croak(Nullch);
+   croak(NULL);
 
 =cut
 */
@@ -1517,7 +1517,7 @@ Perl_my_setenv(pTHX_ const char *nam, const char *val)
 	    tmpenv[j] = (char*)safesysmalloc((len+1)*sizeof(char));
 	    Copy(environ[j], tmpenv[j], len+1, char);
 	}
-	tmpenv[max] = Nullch;
+	tmpenv[max] = NULL;
 	environ = tmpenv;		/* tell exec where it is now */
     }
     if (!val) {
@@ -1530,7 +1530,7 @@ Perl_my_setenv(pTHX_ const char *nam, const char *val)
     }
     if (!environ[i]) {			/* does not exist yet */
 	environ = (char**)safesysrealloc(environ, (i+2) * sizeof(char*));
-	environ[i+1] = Nullch;	/* make sure it's null terminated */
+	environ[i+1] = NULL;	/* make sure it's null terminated */
     }
     else
 	safesysfree(environ[i]);
@@ -2871,8 +2871,8 @@ Perl_find_script(pTHX_ const char *scriptname, bool dosearch,
 		 const char *const *const search_ext, I32 flags)
 {
     dVAR;
-    const char *xfound = Nullch;
-    char *xfailed = Nullch;
+    const char *xfound = NULL;
+    char *xfailed = NULL;
     char tmpbuf[MAXPATHLEN];
     register char *s;
     I32 len = 0;
@@ -2894,7 +2894,7 @@ Perl_find_script(pTHX_ const char *scriptname, bool dosearch,
     static const char *const exts[] = { SEARCH_EXTS };
     const char *const *const ext = search_ext ? search_ext : exts;
     int extidx = 0, i = 0;
-    const char *curext = Nullch;
+    const char *curext = NULL;
 #else
     PERL_UNUSED_ARG(search_ext);
 #  define MAX_EXT_LEN 0
@@ -2927,13 +2927,13 @@ Perl_find_script(pTHX_ const char *scriptname, bool dosearch,
 	int idx = 0, deftypes = 1;
 	bool seen_dot = 1;
 
-	const int hasdir = !dosearch || (strpbrk(scriptname,":[</") != Nullch);
+	const int hasdir = !dosearch || (strpbrk(scriptname,":[</") != NULL);
 #  else
     if (dosearch) {
 	int idx = 0, deftypes = 1;
 	bool seen_dot = 1;
 
-	const int hasdir = (strpbrk(scriptname,":[</") != Nullch);
+	const int hasdir = (strpbrk(scriptname,":[</") != NULL);
 #  endif
 	/* The first time through, just add SEARCH_EXTS to whatever we
 	 * already have, so we can check for default file types. */
@@ -3094,12 +3094,12 @@ Perl_find_script(pTHX_ const char *scriptname, bool dosearch,
 		      (xfailed ? "" : " on PATH"),
 		      (xfailed || seen_dot) ? "" : ", '.' not in PATH");
 	    }
-	    scriptname = Nullch;
+	    scriptname = NULL;
 	}
 	Safefree(xfailed);
 	scriptname = xfound;
     }
-    return (scriptname ? savepv(scriptname) : Nullch);
+    return (scriptname ? savepv(scriptname) : NULL);
 }
 
 #ifndef PERL_GET_CONTEXT_DEFINED