diff --git a/C/c_interface.c b/C/c_interface.c
index 8968a0295..a42294052 100755
--- a/C/c_interface.c
+++ b/C/c_interface.c
@@ -1732,7 +1732,7 @@ X_API bool YAP_LeaveGoal(bool backtrack, YAP_dogoalinfo *dgi) {
 
   BACKUP_MACHINE_REGS();
   myB = (choiceptr)(LCL0 - dgi->b);
-  if (B < myB) {
+  if (B > myB) {
     /* someone cut us */
     return FALSE;
   }
diff --git a/C/cdmgr.c b/C/cdmgr.c
index 72ca6d06a..791998a3e 100644
--- a/C/cdmgr.c
+++ b/C/cdmgr.c
@@ -2534,6 +2534,24 @@ static Int
   // return (out);
 }
 
+static Int
+    p_is_opaque_predicate(USES_REGS1) { /* '$is_multifile'(+S,+Mod)	 */
+  PredEntry *pe;
+  Term t1 = Deref(ARG1);
+  bool out;
+
+  // pe = Yap_get_pred(t1, Deref(ARG2), "system_predicate");
+  // if (!pe)
+  pe = Yap_get_pred(t1, Deref(ARG2), "system_predicate");
+  // if (!pe) pe = Yap_get_pred(t1, USER_MODULE, "system_predicate");
+  if (EndOfPAEntr(pe))
+    return FALSE;
+  return (pe->ModuleOfPred == 0 ||
+	  pe->PredFlags & (SystemPredFlags|ForeignPredFlags));
+  UNLOCKPE(44, pe);
+  return (out);
+}
+
 static Int p_is_thread_local(USES_REGS1) { /* '$is_dynamic'(+P)	 */
   PredEntry *pe;
   bool out;
@@ -4724,6 +4742,8 @@ void Yap_InitCdMgr(void) {
                 SafePredFlag | SyncPredFlag);
   Yap_InitCPred("$is_system_predicate", 2, p_is_system_predicate,
                 TestPredFlag | SafePredFlag);
+  Yap_InitCPred("$is_opaque_predicate", 2, p_is_opaque_predicate,
+                TestPredFlag | SafePredFlag);
   Yap_InitCPred("$new_discontiguous", 3, p_new_discontiguous,
                 SafePredFlag | SyncPredFlag);
   Yap_InitCPred("$is_discontiguous", 2, p_is_discontiguous,
diff --git a/pl/debug.yap b/pl/debug.yap
index dd6b96dc7..540a63770 100644
--- a/pl/debug.yap
+++ b/pl/debug.yap
@@ -604,7 +604,7 @@ be lost.
 	 '$spycall_f'(G, M, CalledFromDebugger, InRedo).
 
 '$spycall_f'(G, M, _, _) :-
-	( '$is_system_predicate'(G,M) ; '$tabled_predicate'(G,M) ),
+	( '$is_opaque_predicate'(G,M) ; '$tabled_predicate'(G,M) ),
 	!,
 	'$continue_debugging_goal'(yes, '$execute_nonstop'(G,M)).
 '$spycall_f'(G, M, CalledFromDebugger, InRedo) :-
diff --git a/pl/listing.yap b/pl/listing.yap
index d8ac5c6d6..6d878fe31 100644
--- a/pl/listing.yap
+++ b/pl/listing.yap
@@ -109,6 +109,7 @@ listing(Stream, [MV|MVs]) :- !,
 
 '$do_listing'(Stream, M, Name/Arity) :-
     ( current_predicate(Name, M:Pred),
+      \+ '$is_opaque_predicate'(Pred,M),
       functor( Pred, Name, Arity),
       \+ '$undefined'(Pred, M),
       '$listing'(Name,Arity,M,Stream),