diff --git a/product/CMFActivity/ActivityTool.py b/product/CMFActivity/ActivityTool.py
index 22434ca5ded01dbd21c0c95d019e3b0b70376dcb..583416fb1f5119a3a4f696791f1e8d0c7382f55a 100755
--- a/product/CMFActivity/ActivityTool.py
+++ b/product/CMFActivity/ActivityTool.py
@@ -306,6 +306,7 @@ class ActivityTool (Folder, UniqueObject):
       self._v_activity_buffer.deferredQueueMessage(self, activity, message)
 
     def deferredDeleteMessage(self, activity, message):
+      if not hasattr(self, '_v_activity_buffer'): self._v_activity_buffer = ActivityBuffer()
       self._v_activity_buffer.deferredDeleteMessage(self, activity, message)
 
     def getRegisteredMessageList(self, activity):