diff --git a/C/text.c b/C/text.c
index 2f570c5bd..a71e3f7c3 100644
--- a/C/text.c
+++ b/C/text.c
@@ -463,14 +463,14 @@ read_Text( void *buf, seq_tv_t *inp, encoding_t *enc, int *minimal, size_t *leng
 #endif
   case YAP_STRING_CHARS:
     *enc = YAP_CHAR;
-    if (inp->sz)
+    if (inp->type & YAP_STRING_NCHARS)
       *lengp = inp->sz;
     else
       *lengp = strlen(inp->val.c);
     return (void *)inp->val.c;
   case YAP_STRING_WCHARS:
     *enc = YAP_WCHAR;
-    if (inp->sz)
+    if (inp->type & YAP_STRING_NCHARS)
       *lengp = inp->sz;
     else
       *lengp = wcslen(inp->val.w);
diff --git a/H/YapText.h b/H/YapText.h
index 24768605a..10ff66475 100644
--- a/H/YapText.h
+++ b/H/YapText.h
@@ -294,6 +294,7 @@ Yap_CharsToAtom( const char *s USES_REGS )
   seq_tv_t inp, out;
 
   inp.val.c = s;
+  inp.sz = 0;
   inp.type = YAP_STRING_CHARS;
   out.type = YAP_STRING_ATOM;
   if (!Yap_CVT_Text(&inp, &out PASS_REGS))
@@ -307,6 +308,7 @@ Yap_CharsToListOfAtoms( const char *s USES_REGS )
   seq_tv_t inp, out;
 
   inp.val.c = s;
+  inp.sz = 0;
   inp.type = YAP_STRING_CHARS;
   out.type = YAP_STRING_ATOMS;
   if (!Yap_CVT_Text(&inp, &out PASS_REGS))
@@ -320,6 +322,7 @@ Yap_CharsToListOfCodes( const char *s USES_REGS )
   seq_tv_t inp, out;
 
   inp.val.c = s;
+  inp.sz = 0;
   inp.type = YAP_STRING_CHARS;
   out.type = YAP_STRING_CODES;
   if (!Yap_CVT_Text(&inp, &out PASS_REGS))
@@ -333,6 +336,7 @@ Yap_CharsToString( const char *s USES_REGS )
   seq_tv_t inp, out;
 
   inp.val.c = s;
+  inp.sz = 0;
   inp.type = YAP_STRING_CHARS;
   out.type = YAP_STRING_STRING;
   if (!Yap_CVT_Text(&inp, &out PASS_REGS))
@@ -346,6 +350,7 @@ Yap_CharsToTDQ( const char *s, Term mod USES_REGS )
   seq_tv_t inp, out;
 
   inp.val.c = s;
+  inp.sz = 0;
   inp.type = YAP_STRING_CHARS;
   inp.mod = mod;
   out.type = mod_to_type(mod PASS_REGS);
@@ -689,7 +694,7 @@ static inline Atom
 Yap_StringToAtom(Term t0 USES_REGS)
 {
   seq_tv_t inp, out;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.val.t = t0;
   inp.type = YAP_STRING_STRING;
   out.type = YAP_STRING_ATOM;
@@ -702,7 +707,7 @@ static inline Atom
 Yap_StringSWIToAtom(Term t0 USES_REGS)
 {
   seq_tv_t inp, out;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.val.t = t0;
   inp.type = YAP_STRING_STRING|YAP_STRING_ATOM|YAP_STRING_INT|YAP_STRING_FLOAT|YAP_STRING_BIG|YAP_STRING_ATOMS_CODES|YAP_STRING_TERM;
   out.type = YAP_STRING_ATOM;
@@ -715,7 +720,7 @@ static inline size_t
 Yap_StringToAtomic(Term t0 USES_REGS)
 {
   seq_tv_t inp, out;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.val.t = t0;
   inp.type = YAP_STRING_STRING;
   out.type = YAP_STRING_ATOM|YAP_STRING_INT|YAP_STRING_FLOAT|YAP_STRING_BIG|YAP_STRING_TERM;
@@ -728,7 +733,7 @@ static inline size_t
 Yap_StringToLength(Term t0 USES_REGS)
 {
   seq_tv_t inp, out;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.val.t = t0;
   inp.type = YAP_STRING_STRING;
   out.type = YAP_STRING_LENGTH;
@@ -741,7 +746,7 @@ static inline size_t
 Yap_StringToListOfAtoms(Term t0 USES_REGS)
 {
   seq_tv_t inp, out;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.val.t = t0;
   inp.type = YAP_STRING_STRING;
   out.type = YAP_STRING_ATOMS;
@@ -754,7 +759,7 @@ static inline size_t
 Yap_StringSWIToListOfAtoms(Term t0 USES_REGS)
 {
   seq_tv_t inp, out;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.val.t = t0;
   inp.type = YAP_STRING_STRING|YAP_STRING_ATOM|YAP_STRING_INT|YAP_STRING_FLOAT|YAP_STRING_BIG|YAP_STRING_ATOMS_CODES|YAP_STRING_TERM;
   out.type = YAP_STRING_ATOMS;
@@ -768,7 +773,7 @@ Yap_StringToListOfCodes(Term t0 USES_REGS)
 {
   seq_tv_t inp, out;
   inp.val.t = t0;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.type = YAP_STRING_STRING;
   out.type = YAP_STRING_CODES;
   if (!Yap_CVT_Text(&inp, &out PASS_REGS))
@@ -793,7 +798,7 @@ Yap_StringToNumber(Term t0 USES_REGS)
 {
   seq_tv_t inp, out;
   inp.val.t = t0;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.type = YAP_STRING_STRING;
   out.type = YAP_STRING_INT|YAP_STRING_FLOAT|YAP_STRING_BIG|YAP_STRING_TERM;
   if (!Yap_CVT_Text(&inp, &out PASS_REGS))
@@ -806,7 +811,7 @@ Yap_WCharsToListOfCodes(const wchar_t *s USES_REGS)
 {
   seq_tv_t inp, out;
   inp.val.w = s;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.type = YAP_STRING_WCHARS;
   out.type = YAP_STRING_CODES;
   if (!Yap_CVT_Text(&inp, &out PASS_REGS))
@@ -821,7 +826,7 @@ Yap_WCharsToTDQ( wchar_t *s, Term mod USES_REGS )
 
   inp.val.w = s;
   inp.type = YAP_STRING_WCHARS;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.mod = mod;
   out.type = mod_to_type(mod PASS_REGS);
   if (!Yap_CVT_Text(&inp, &out PASS_REGS))
@@ -834,7 +839,7 @@ Yap_WCharsToString(const wchar_t *s USES_REGS)
 {
   seq_tv_t inp, out;
   inp.val.w = s;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.type = YAP_STRING_WCHARS;
   out.type = YAP_STRING_STRING;
   if (!Yap_CVT_Text(&inp, &out PASS_REGS))
@@ -848,10 +853,10 @@ Yap_ConcatAtoms(Term t1, Term t2 USES_REGS)
   seq_tv_t inpv[2], out;
   inpv[0].val.t = t1;
   inpv[0].type = YAP_STRING_ATOM;
-  inpv[0].sz = -1;
+  inpv[0].sz = 0;
   inpv[1].val.t = t2;
   inpv[1].type = YAP_STRING_ATOM;
-  inpv[1].sz = -1;
+  inpv[1].sz = 0;
   out.type = YAP_STRING_ATOM;
   if (!Yap_Concat_Text(2, inpv, &out PASS_REGS))
     return NULL;
@@ -864,10 +869,10 @@ Yap_ConcatAtomics(Term t1, Term t2 USES_REGS)
   seq_tv_t inpv[2], out;
   inpv[0].val.t = t1;
   inpv[0].type = YAP_STRING_STRING|YAP_STRING_ATOM|YAP_STRING_INT|YAP_STRING_FLOAT|YAP_STRING_BIG|YAP_STRING_TERM;
-  inpv[0].sz = -1;
+  inpv[0].sz = 0;
   inpv[1].val.t = t2;
   inpv[1].type = YAP_STRING_STRING|YAP_STRING_ATOM|YAP_STRING_INT|YAP_STRING_FLOAT|YAP_STRING_BIG|YAP_STRING_TERM;
-  inpv[1].sz = -1;
+  inpv[1].sz = 0;
   out.type = YAP_STRING_ATOM;
   if (!Yap_Concat_Text(2, inpv, &out PASS_REGS))
     return NULL;
@@ -880,10 +885,10 @@ Yap_ConcatStrings(Term t1, Term t2 USES_REGS)
   seq_tv_t inpv[2], out;
   inpv[0].val.t = t1;
   inpv[0].type = YAP_STRING_STRING;
-  inpv[0].sz = -1;
+  inpv[0].sz = 0;
   inpv[1].val.t = t2;
   inpv[1].type = YAP_STRING_STRING;
-  inpv[1].sz = -1;
+  inpv[1].sz = 0;
   out.type = YAP_STRING_STRING;
   if (!Yap_Concat_Text(2, inpv, &out PASS_REGS))
     return 0L;
@@ -900,11 +905,11 @@ Yap_SpliceAtom(Term t1, Atom ats[], size_t cut, size_t max USES_REGS)
   cuts[1] = max;
   inp.type = YAP_STRING_ATOM;
   inp.val.t = t1;
-  inp.sz = -1;
+  inp.sz = 0;
   outv[0].type = YAP_STRING_ATOM;
-  outv[0].sz = -1;
+  outv[0].sz = 0;
   outv[1].type = YAP_STRING_ATOM;
-  outv[1].sz = -1;
+  outv[1].sz = 0;
   if (!Yap_Splice_Text(2, cuts, &inp, NULL, outv PASS_REGS))
     return NULL;
   ats[0] = outv[0].val.a;
@@ -918,13 +923,13 @@ Yap_SubtractHeadAtom(Term t1, Term th USES_REGS)
   seq_tv_t outv[2], inp;
   inp.type = YAP_STRING_ATOM;
   inp.val.t = t1;
-  inp.sz = -1;
+  inp.sz = 0;
   outv[0].type = YAP_STRING_ATOM;
   outv[0].val.t = th;
-  outv[0].sz = -1;
+  outv[0].sz = 0;
   outv[1].type = YAP_STRING_ATOM;
   outv[1].val.t = 0;
-  outv[1].sz = -1;
+  outv[1].sz = 0;
   if (!Yap_Splice_Text(2, NULL, &inp, NULL, outv PASS_REGS))
     return NULL;
   return outv[1].val.a;
@@ -937,10 +942,10 @@ Yap_SubtractTailAtom(Term t1, Term th USES_REGS)
   seq_tv_t outv[2], inp;
   inp.type = YAP_STRING_ATOM;
   inp.val.t = t1;
-  inp.sz = -1;
+  inp.sz = 0;
   outv[0].type = YAP_STRING_ATOM;
   outv[0].val.t = 0;
-  outv[0].sz = -1;
+  outv[0].sz = 0;
   outv[1].type = YAP_STRING_ATOM;
   outv[1].val.t = th;
   if (!Yap_Splice_Text(2, NULL, &inp, NULL, outv PASS_REGS))
@@ -955,10 +960,10 @@ Yap_SpliceString(Term t1, Term ts[], size_t cut, size_t max USES_REGS)
   size_t cuts[2];
   inp.type = YAP_STRING_STRING;
   inp.val.t = t1;
-  inp.sz = -1;
+  inp.sz = 0;
   outv[0].type = YAP_STRING_STRING;
   outv[1].type = YAP_STRING_STRING;
-  outv[1].sz = -1;
+  outv[1].sz = 0;
   cuts[0] = cut;
   cuts[1] = max;
   if (!Yap_Splice_Text(2, cuts, &inp, NULL, outv PASS_REGS))
@@ -974,13 +979,13 @@ Yap_SubtractHeadString(Term t1, Term th USES_REGS)
   seq_tv_t outv[2], inp;
   inp.type = YAP_STRING_STRING;
   inp.val.t = t1;
-  inp.sz = -1;
+  inp.sz = 0;
   outv[0].type = YAP_STRING_STRING;
   outv[0].val.t = th;
-  outv[0].sz = -1;
+  outv[0].sz = 0;
   outv[1].type = YAP_STRING_STRING;
   outv[1].val.t = 0;
-  outv[1].sz = -1;
+  outv[1].sz = 0;
   if (!Yap_Splice_Text(2, NULL, &inp, NULL, outv PASS_REGS))
     return 0L;
   return outv[1].val.t;
@@ -992,10 +997,10 @@ Yap_SubtractTailString(Term t1, Term th USES_REGS)
   seq_tv_t outv[2], inp;
   inp.type = YAP_STRING_STRING;
   inp.val.t = t1;
-  inp.sz = -1;
+  inp.sz = 0;
   outv[0].type = YAP_STRING_STRING;
   outv[0].val.t = 0;
-  outv[0].sz = -1;
+  outv[0].sz = 0;
   outv[1].type = YAP_STRING_STRING;
   outv[1].val.t = th;
   if (!Yap_Splice_Text(2, NULL, &inp, NULL, outv PASS_REGS))
diff --git a/os/pl-prologflag.c b/os/pl-prologflag.c
index b1a744fce..29f593808 100644
--- a/os/pl-prologflag.c
+++ b/os/pl-prologflag.c
@@ -118,10 +118,11 @@ indexOfBoolMask(unsigned int mask)
   return i;
 }
 
-
 void
 setPrologFlag(const char *name, int flags, ...)
 { GET_LD
+    if (!strcmp("file_name_variables",name))
+      printf("hello\n");
   atom_t an = PL_new_atom(name);
   prolog_flag *f;
   Symbol s;
diff --git a/packages/real b/packages/real
index a383bfd51..5a72fe49e 160000
--- a/packages/real
+++ b/packages/real
@@ -1 +1 @@
-Subproject commit a383bfd51144172fdea8463bd56e9308742e5de2
+Subproject commit 5a72fe49e5a5c651a890a388eb967b83da8e2c52
diff --git a/pl/absf.yap b/pl/absf.yap
index b7f4809c1..3b4845a7b 100644
--- a/pl/absf.yap
+++ b/pl/absf.yap
@@ -224,7 +224,7 @@ absolute_file_name(File,Opts,TrueFileName) :-
 	(Type == directory ->
 	 exists_directory(F0)
 	;
-	 \+ exists_directory(F0) % if it has a type cannot be a directory.
+	\+ exists_directory(F0) % if it has a type cannot be a directory.
 	).
 
 '$add_extensions'([Ext|_],File,F) :-