diff --git a/C/init.c b/C/init.c
index 95ab88b4c..2b7fb45b2 100755
--- a/C/init.c
+++ b/C/init.c
@@ -196,6 +196,52 @@ int Yap_IsOpType(char *type) {
   return (i <= 7);
 }
 
+static OpEntry *
+fetchOpForModule(AtomEntry *ae, Term tmod )
+{
+  OpEntry *oinfo = NULL;
+  PropEntry **prev = &ae->PropsOfAE;
+  PropEntry *pp = ae->PropsOfAE;
+  
+  while (!EndOfPAEntr(pp)) {
+    OpEntry *info = RepOpProp(pp);
+    if (!info)
+      return NULL;
+    if (pp->KindOfPE == OpProperty) {
+      if (tmod == PROLOG_MODULE) {
+        if (info->OpModule != PROLOG_MODULE) {
+          info->Infix = info->Prefix = info->Posfix = 0;
+          info->OpModule = tmod;
+          if (oinfo == NULL)
+            oinfo = info;
+          else {
+            pp = RepProp(pp->NextOfPE);
+            *prev = pp;
+            //Yap_FreeCodeSpace( oinfo );
+            continue;
+          }
+        } else{
+          if (oinfo) {
+            // should never happen?
+            oinfo->Infix = info->Infix;
+            oinfo->Prefix = info->Prefix;
+            oinfo->Posfix = info->Posfix;
+            pp = RepProp(pp->NextOfPE);
+            *prev = pp;
+            //            Yap_FreeCodeSpace( oinfo );
+            continue;
+          }
+          return info;
+        }
+      } else if (info->OpModule == tmod)
+        return info;
+    }
+    prev = & pp->NextOfPE;
+    pp = RepProp(pp->NextOfPE);
+  }
+  return oinfo;
+}
+
 static int OpDec(int p, const char *type, Atom a, Term m) {
   int i;
   AtomEntry *ae = RepAtom(a);
@@ -203,8 +249,6 @@ static int OpDec(int p, const char *type, Atom a, Term m) {
 
   if (m == TermProlog)
     m = PROLOG_MODULE;
-  else if (m == USER_MODULE)
-    m = PROLOG_MODULE;
   for (i = 1; i <= 7; ++i)
     if (strcmp(type, optypes[i]) == 0)
       break;
@@ -220,7 +264,7 @@ static int OpDec(int p, const char *type, Atom a, Term m) {
       p |= DcrrpFlag;
   }
   WRITE_LOCK(ae->ARWLock);
-  info = Yap_GetOpPropForAModuleHavingALock(ae, m);
+  info = fetchOpForModule(ae, m);
   if (EndOfPAEntr(info)) {
     info = (OpEntry *)Yap_AllocAtomSpace(sizeof(OpEntry));
     info->KindOfPE = Ord(OpProperty);
@@ -239,6 +283,7 @@ static int OpDec(int p, const char *type, Atom a, Term m) {
     WRITE_LOCK(info->OpRWLock);
     WRITE_UNLOCK(ae->ARWLock);
   }
+  
   if (i <= 3) {
     if (trueGlobalPrologFlag(ISO_FLAG) &&
         info->Posfix != 0) /* there is a posfix operator */ {
@@ -249,7 +294,6 @@ static int OpDec(int p, const char *type, Atom a, Term m) {
     }
     info->Infix = p;
   } else if (i <= 5) {
-
     if (trueGlobalPrologFlag(ISO_FLAG) &&
         info->Infix != 0) /* there is an infix operator */ {
       /* ISO dictates */
diff --git a/H/Yatom.h b/H/Yatom.h
index 08d1dfb9b..5c7a3231c 100755
--- a/H/Yatom.h
+++ b/H/Yatom.h
@@ -266,16 +266,17 @@ INLINE_ONLY inline EXTERN int IsWideAtom(Atom at) {
 
 /*	Module property 						*/
 typedef struct mod_entry {
-  Prop NextOfPE;                /* used to chain properties            */
-  PropFlags KindOfPE;           /* kind of property                    */
-  struct pred_entry *PredForME; /* index in module table               */
-  Atom AtomOfME;                /* module's name	                */
-  Atom OwnerFile;               /* module's owner file	                */
+  Prop NextOfPE;                /** used to chain properties            */
+  PropFlags KindOfPE;           /** kind of property                    */
+  struct pred_entry *PredForME; /** list of predicates for that module               */
+  Atom AtomOfME;                /** module's name	                */
+  Atom OwnerFile;               /** module's owner file	                */
 #if defined(YAPOR) || defined(THREADS)
-  rwlock_t ModRWLock; /* a read-write lock to protect the entry */
+  rwlock_t ModRWLock; /** a read-write lock to protect the entry */
 #endif
-  unsigned int flags;       /* Module local flags (from SWI compat) */
-  struct mod_entry *NextME; /* next module                         */
+  Term  ParentForME;   /** the module we wer created from */
+  unsigned int flags;       /** Module local flags (from SWI compat): includes ops, strings */
+  struct mod_entry *NextME; /** next module                         */
 } ModEntry;
 
 #if USE_OFFSETS_IN_PROPS
@@ -391,12 +392,12 @@ INLINE_ONLY inline EXTERN PropFlags IsOpProperty(int flags) {
 
 typedef enum { INFIX_OP = 0, POSFIX_OP = 1, PREFIX_OP = 2 } op_type;
 
-OpEntry *Yap_GetOpProp(Atom, op_type CACHE_TYPE);
+ OpEntry *Yap_GetOpProp(Atom, op_type, Term CACHE_TYPE);
 
-int Yap_IsPrefixOp(Atom, int *, int *);
+int Yap_IsPrefixOp(Atom, int *, int *, Term);
 int Yap_IsOp(Atom);
-int Yap_IsInfixOp(Atom, int *, int *, int *);
-int Yap_IsPosfixOp(Atom, int *, int *);
+int Yap_IsInfixOp(Atom, int *, int *, int *, Term);
+int Yap_IsPosfixOp(Atom, int *, int *, Term);
 
 /* defines related to operator specifications				*/
 #define MaskPrio 0x0fff