diff --git a/product/ERP5Type/Cache.py b/product/ERP5Type/Cache.py
index c87fcf1c13838ac967fe2d666e2e232c722734b7..115ebf3e9bd16dd83a306c18d4f72ca19f125dfa 100644
--- a/product/ERP5Type/Cache.py
+++ b/product/ERP5Type/Cache.py
@@ -280,4 +280,6 @@ def generateCacheIdWithoutFirstArg(method_id, *args, **kwd):
 
 def caching_class_method_decorator(*args, **kw):
   kw.setdefault('cache_id_func', generateCacheIdWithoutFirstArg)
-  return lambda m: lambda *a, **k: CachingMethod(m, *args, **kw)(*a, **k)
+  def wrapped(method):
+    return lambda *a, **k: CachingMethod(method, *args, **kw)(*a, **k)
+  return wrapped