diff --git a/Objective-J/Debug.js b/Objective-J/Debug.js
index 532afc6f2..d8583f634 100644
--- a/Objective-J/Debug.js
+++ b/Objective-J/Debug.js
@@ -185,7 +185,7 @@ GLOBAL(objj_typecheck_decorator) = function(msgSend)
         if (!aReceiver)
             return msgSend.apply(this, arguments);
 
-        var types = aReceiver.isa.method_dtable[aSelector].types;
+        var types = aReceiver.isa.method_dtable[aSelector].method_types;
         for (var i = 2; i < arguments.length; i++)
         {
             try