diff --git a/product/ERP5Type/Cache.py b/product/ERP5Type/Cache.py
index 7834ea6e090730792118648a59841b52cfe6721f..53aa89e80f446b9cbf7e1422759a2de43e7dab31 100755
--- a/product/ERP5Type/Cache.py
+++ b/product/ERP5Type/Cache.py
@@ -71,7 +71,7 @@ class CachingMethod:
         since this is done once per 100 calls.
   """
   # Use this global variable to store cached objects.
-  cached_object_dict = PersistentMapping()
+  cached_object_dict = {}
   
   def __init__(self, callable_object, id = None, cache_duration = 180):
     """