diff --git a/lib/libmocha/et_moz.c b/lib/libmocha/et_moz.c
index 8aa3942f0d4e..e80aabe32549 100644
--- a/lib/libmocha/et_moz.c
+++ b/lib/libmocha/et_moz.c
@@ -3004,7 +3004,7 @@ ET_JSCFExecute(MWContext *context, const char *script_name,
     JSCFResult *res;
     MozillaEvent_JSCFExecute* event = PR_NEW(MozillaEvent_JSCFExecute);
     if(!event)
-	return NULL;
+	return (JSCFResult) 0;
 
     PR_InitEvent(&event->ce.event, NULL,
 		 (PRHandleEventProc)et_HandleEvent_JSCFExecute,