diff --git a/C/c_interface.c b/C/c_interface.c
index 16aeffa98..f8e41d353 100755
--- a/C/c_interface.c
+++ b/C/c_interface.c
@@ -3597,6 +3597,7 @@ int YAP_OpInfo(Atom at, Term module, int opkind, int *yap_type, int *prio)
     }
   }
   *yap_type = n;
+  WRITE_UNLOCK(ae->ARWLock);
   return 1;
 }
 
diff --git a/packages/PLStream/pl-yap.c b/packages/PLStream/pl-yap.c
index 6fc83e22e..f59e1a035 100755
--- a/packages/PLStream/pl-yap.c
+++ b/packages/PLStream/pl-yap.c
@@ -517,8 +517,9 @@ currentOperator(Module m, atom_t name, int kind, int *type, int *priority)
   default:
     opkind = 1;
   }
-  if (!YAP_OpInfo(YAP_AtomFromSWIAtom(name), mod, opkind, &yap_type, priority))
+  if (!YAP_OpInfo(YAP_AtomFromSWIAtom(name), mod, opkind, &yap_type, priority)) {
     return FALSE;
+  }
   switch(yap_type) {
   case 1:
     *type = OP_XFX;