diff --git a/product/ERP5Type/Constraint/PropertyTypeValidity.py b/product/ERP5Type/Constraint/PropertyTypeValidity.py
index 8848f7eaae2c896ae5913f612e9a2a6d31d9de3a..c6f5f609c9030204ee5709a26d5ffa4d84e88f4e 100644
--- a/product/ERP5Type/Constraint/PropertyTypeValidity.py
+++ b/product/ERP5Type/Constraint/PropertyTypeValidity.py
@@ -45,6 +45,7 @@ class PropertyTypeValidity(Constraint):
 
   # Initialize type dict
   _type_dict = {
+    'object':             (type('a'), ),
     'string':             (type('a'), ),
     'text':               (type('a'), ),
     'int':                (type(1), ),