diff --git a/C/adtdefs.c b/C/adtdefs.c
index 04083060d..a400a1b84 100755
--- a/C/adtdefs.c
+++ b/C/adtdefs.c
@@ -812,6 +812,10 @@ Yap_NewPredPropByFunctor(FunctorEntry *fe, Term cur_mod)
   else
     p->ModuleOfPred = cur_mod;
   //TRUE_FUNC_WRITE_LOCK(fe);
+#if DEBUG_NEW_FUNCTOR
+  if (!strcmp(fe->NameOfFE->StrOfAE, "library_directory"))
+    jmp_deb(1);
+#endif
   INIT_LOCK(p->PELock);
   p->KindOfPE = PEProp;
   p->ArityOfPE = fe->ArityOfFE;
diff --git a/C/modules.c b/C/modules.c
index 27d16502e..bd424d33a 100644
--- a/C/modules.c
+++ b/C/modules.c
@@ -263,6 +263,21 @@ p_strip_module( USES_REGS1 )
     Yap_unify(ARG2, tmod);      
 }
 
+static Int
+p_system_module( USES_REGS1 )
+{
+  Term t1 = Deref(ARG1);
+  if (t1 == PROLOG_MODULE) {
+    return TRUE;
+  }
+  return t1 == TermProlog ||
+    t1 == IDB_MODULE ||
+    t1 == IDB_MODULE ||
+    t1 == ATTRIBUTES_MODULE ||
+    t1 == SYSTEM_MODULE ||
+    t1 == GLOBALS_MODULE;
+}
+
 static Int
 p_context_module( USES_REGS1 )
 {
@@ -336,6 +351,7 @@ Yap_InitModulesC(void)
   Yap_InitCPred("$change_module", 1, p_change_module, SafePredFlag|SyncPredFlag);
   Yap_InitCPred("strip_module", 3, p_strip_module, SafePredFlag|SyncPredFlag);
   Yap_InitCPred("context_module", 1, p_context_module, 0);
+  Yap_InitCPred("$system_module", 1, p_system_module, 0);
   Yap_InitCPredBack("$all_current_modules", 1, 1, init_current_module, cont_current_module,
 		SafePredFlag|SyncPredFlag);
 }
diff --git a/packages/prism/src/c/core/idtable.c b/packages/prism/src/c/core/idtable.c
index 7f1cbe3f2..0fac9d535 100644
--- a/packages/prism/src/c/core/idtable.c
+++ b/packages/prism/src/c/core/idtable.c
@@ -148,11 +148,11 @@ IDNUM id_table_retrieve(const ID_TABLE *this, TERM term)
 
 IDNUM id_table_register(ID_TABLE *this, TERM term)
 {
-    BPULONG hash;
+  //    BPULONG hash;
     IDNUM i;
 
     term = term_pool_register(this->store, term);
-    hash = (BPULONG)(term);
+    //hash = (BPULONG)(term);
 
     i = id_table_search(this, term);
     if (i == ID_NONE) {
diff --git a/pl/modules.yap b/pl/modules.yap
index 89a9fdae5..2b2db1e32 100755
--- a/pl/modules.yap
+++ b/pl/modules.yap
@@ -1063,23 +1063,21 @@ module_property(Mod, file(F)) :-
 module_property(Mod, exports(Es)) :-
 	recorded('$module','$module'(_,Mod,Es,_),_).
 
-'$module_class'(system, L) :- '$system_module'(L).
-'$module_class'(library, L) :- '$library_module'(L).
-'$module_class'(user, L) :- '$user_module'(L).
-'$module_class'(temporary, L) :- fail.
-'$module_class'(test, L) :- fail.
-'$module_class'(development, L) :- fail.
-
-'$system_module'(prolog).
-'$system_module'(system).
+'$module_class'(Mod, system) :- '$system_module'( Mod ).
+'$module_class'(Mod, library) :- '$library_module'( Mod ).
+'$module_class'(Mod, user) :- '$user_module'( Mod ).
+'$module_class'(_, temporary) :- fail.
+'$module_class'(_, test) :- fail.
+'$module_class'(_, development) :- fail.
 
 '$library_module'(M1) :-
 	recorded('$module','$module'(F, M1, _MyExports,_Line),_),
-	library_directory(D),
+	user:library_directory(D),
 	sub_atom(F, 0, _, _, D).
 
-'$user_module'(_).
-
+'$user_module'( Mod ) :- 
+    \+ '$library_module'( Mod),
+    \+ '$system_module'( Mod).
 
 ls_imports :-
 	recorded('$import','$import'(M0,M,G0,G,_N,_K),_R),