diff --git a/product/ERP5Type/TransactionalVariable.py b/product/ERP5Type/TransactionalVariable.py
index e9160a28b6772c8f8857b698e09d00a8b575e7cf..7ccce4e2386b63c3c1841463d2de55d6cc65cc0b 100644
--- a/product/ERP5Type/TransactionalVariable.py
+++ b/product/ERP5Type/TransactionalVariable.py
@@ -63,6 +63,8 @@ class TransactionalVariable(TM, IterableUserDict):
   """TransactionalVariable provides a dict-like look-n-feel.
   This class must not be used directly outside.
   """
+  _finalize = None
+
   def _begin(self, *ignored):
     """It is required to attach this instance to somewhere in
     ZODB so that _finish or _abort will be called at the end