diff --git a/product/ERP5Type/Base.py b/product/ERP5Type/Base.py
index 87a033de3c9e671f0c233882d92f382dd8e97a70..a338833b0d1e4c801750ba1398c275ac0e66a2f9 100644
--- a/product/ERP5Type/Base.py
+++ b/product/ERP5Type/Base.py
@@ -324,6 +324,11 @@ class PropertyHolder(object):
     self.security = ClassSecurityInfo() # We create a new security info object
     self.workflow_method_registry = {}
 
+    self._categories = []
+    self._properties = []
+    self._constraints = []
+    self.constraints = []
+
   def _getItemList(self):
     return [x for x in self.__dict__.items() if x[0] not in
         PropertyHolder.RESERVED_PROPERTY_SET]