Index: src/main/org/codehaus/groovy/runtime/ConversionHandler.java
===================================================================
--- src/main/org/codehaus/groovy/runtime/ConversionHandler.java	(revision 13784)
+++ src/main/org/codehaus/groovy/runtime/ConversionHandler.java	(working copy)
@@ -68,7 +68,7 @@
      */
     public Object invoke(Object proxy, Method method, Object[] args)
     throws Throwable {
-        if(!isObjectMethod(method)){
+    	if(!isObjectMethod(method) || method.getName().equals("toString")) {
             return invokeCustom(proxy,method,args);
         }
         try {