diff --git a/H/Yap.h b/H/Yap.h
index 99009f946..d4a8b36ad 100755
--- a/H/Yap.h
+++ b/H/Yap.h
@@ -556,7 +556,7 @@ typedef struct opcode_tab_entry
 {
   OPCODE opc;
   op_numbers opnum;
-} opentry;
+} op_entry;
 
 #endif
 
diff --git a/H/dhstruct.h b/H/dhstruct.h
index 90ee4b667..8039fa41d 100644
--- a/H/dhstruct.h
+++ b/H/dhstruct.h
@@ -277,6 +277,9 @@
 #define ParserErrorStyle Yap_heap_regs->parser_error_style
 
 #define Yap_LibDir Yap_heap_regs->yap_lib_dir
+#define Yap_ForeignDir Yap_heap_regs->yap_foreign_dir
+#define Yap_CommonsDir Yap_heap_regs->yap_commons_dir
+#define Yap_BinDir Yap_heap_regs->yap_bin_dir
 
 #define LastWtimePtr Yap_heap_regs->last_wtime
 
diff --git a/H/hstruct.h b/H/hstruct.h
index 0872294f8..adfcc17ff 100755
--- a/H/hstruct.h
+++ b/H/hstruct.h
@@ -61,7 +61,7 @@
 
 
 #if USE_THREADED_CODE
-  opentry  *op_rtable;
+  op_entry  *op_rtable;
 #endif
 
   OPCODE  execute_cpred_op_code;
@@ -276,7 +276,10 @@
 
   int  parser_error_style;
 
-  char  *yap_lib_dir;
+  const char  *yap_lib_dir;
+  const char  *yap_foreign_dir;
+  const char  *yap_commons_dir;
+  const char  *yap_bin_dir;
 
   void  *last_wtime;
 
diff --git a/H/ihstruct.h b/H/ihstruct.h
index 96b1cb637..0ade80f05 100644
--- a/H/ihstruct.h
+++ b/H/ihstruct.h
@@ -277,6 +277,9 @@
   ParserErrorStyle = EXCEPTION_ON_PARSER_ERROR;
 
   Yap_LibDir = NULL;
+  Yap_ForeignDir = NULL;
+  Yap_CommonsDir = NULL;
+  Yap_BinDir = NULL;
 
   LastWtimePtr = NULL;
 
diff --git a/H/rhstruct.h b/H/rhstruct.h
index aea230d60..f0fd7bc90 100644
--- a/H/rhstruct.h
+++ b/H/rhstruct.h
@@ -276,7 +276,10 @@
 
 
 
-  Yap_LibDir = CodeCharPAdjust(Yap_LibDir);
+  Yap_LibDir = CodeConstCharPAdjust(Yap_LibDir);
+  Yap_ForeignDir = CodeConstCharPAdjust(Yap_ForeignDir);
+  Yap_CommonsDir = CodeConstCharPAdjust(Yap_CommonsDir);
+  Yap_BinDir = CodeConstCharPAdjust(Yap_BinDir);
 
   LastWtimePtr = CodeVoidPAdjust(LastWtimePtr);
 
diff --git a/H/sshift.h b/H/sshift.h
index 561993921..efe1712ea 100644
--- a/H/sshift.h
+++ b/H/sshift.h
@@ -107,6 +107,7 @@
 #define TrailAdjust(P) TrailAdjust__(P PASS_REGS)
 #define HoldEntryAdjust(P) HoldEntryAdjust__(P PASS_REGS)
 #define CodeCharPAdjust(P) CodeCharPAdjust__(P PASS_REGS)
+#define CodeConstCharPAdjust(P) CodeConstCharPAdjust__(P PASS_REGS)
 #define CodeVoidPAdjust(P) CodeVoidPAdjust__(P PASS_REGS)
 #define HaltHookAdjust(P) HaltHookAdjust__(P PASS_REGS)
 #define TokEntryAdjust(P) TokEntryAdjust__(P PASS_REGS)
@@ -720,6 +721,16 @@ CodeCharPAdjust__ (char * addr USES_REGS)
   return addr + LOCAL_HDiff;
 }
 
+INLINE_ONLY inline EXTERN const char * CodeConstCharPAdjust__ (const char * CACHE_TYPE);
+
+INLINE_ONLY inline EXTERN const char *
+CodeConstCharPAdjust__ (const char * addr USES_REGS)
+{
+  if (!addr)
+    return NULL;
+  return addr + LOCAL_HDiff;
+}
+
 INLINE_ONLY inline EXTERN void * CodeVoidPAdjust__ (void * CACHE_TYPE);
 
 INLINE_ONLY inline EXTERN void *
@@ -829,12 +840,12 @@ TermToGlobalOrAtomAdjust__ (Term t USES_REGS)
   return t;
 }
 
-INLINE_ONLY inline EXTERN opentry *OpRTableAdjust__ (opentry * CACHE_TYPE);
+INLINE_ONLY inline EXTERN op_entry *OpRTableAdjust__ (op_entry * CACHE_TYPE);
 
-INLINE_ONLY inline EXTERN opentry *
-OpRTableAdjust__ (opentry * ptr USES_REGS)
+INLINE_ONLY inline EXTERN op_entry *
+OpRTableAdjust__ (op_entry * ptr USES_REGS)
 {
-  return (opentry *) (((opentry *) (CharP (ptr) + LOCAL_HDiff)));
+  return (op_entry *) (((op_entry *) (CharP (ptr) + LOCAL_HDiff)));
 }
 
 INLINE_ONLY inline EXTERN OpEntry *OpEntryAdjust__ (OpEntry * CACHE_TYPE);
diff --git a/misc/HEAPFIELDS b/misc/HEAPFIELDS
index ace67c342..a8a94d8ae 100644
--- a/misc/HEAPFIELDS
+++ b/misc/HEAPFIELDS
@@ -59,7 +59,7 @@ UInt		MaxTrail_		MaxTrail		=0 void
 /* execution info */
 /* OPCODE TABLE, needed to recover op tables */
 #if USE_THREADED_CODE
-opentry		*op_rtable		OP_RTABLE		void	OpRTableAdjust
+op_entry	*op_rtable		OP_RTABLE		void	OpRTableAdjust
 #endif
 
 /* popular opcodes */
@@ -309,10 +309,10 @@ char		*char_conversion_table2	CharConversionTable2	=NULL CodeCharPAdjust
 int		parser_error_style	ParserErrorStyle	=EXCEPTION_ON_PARSER_ERROR void
 
 /* library location.  */
-const char	*yap_lib_dir		Yap_LibDir		=NULL CodeCharPAdjust
-const char	*yap_foreign_dir	Yap_ForeignDir		=NULL CodeCharPAdjust
-const char	*yap_commons_dir	Yap_CommonsDir		=NULL CodeCharPAdjust
-const char	*yap_bin_dir		Yap_BinDir		=NULL CodeCharPAdjust
+const char	*yap_lib_dir		Yap_LibDir		=NULL CodeConstCharPAdjust
+const char	*yap_foreign_dir	Yap_ForeignDir		=NULL CodeConstCharPAdjust
+const char	*yap_commons_dir	Yap_CommonsDir		=NULL CodeConstCharPAdjust
+const char	*yap_bin_dir		Yap_BinDir		=NULL CodeConstCharPAdjust
 
 /* time */
 void		*last_wtime		LastWtimePtr		=NULL CodeVoidPAdjust