diff --git a/product/ERP5Type/Constraint/CategoryMembershipState.py b/product/ERP5Type/Constraint/CategoryMembershipState.py
index 8f45e25c688d644b6ac59cd791bcb9a20db938da..c591e3cf41d220e7b8966d517ae06a08fa1aa88c 100644
--- a/product/ERP5Type/Constraint/CategoryMembershipState.py
+++ b/product/ERP5Type/Constraint/CategoryMembershipState.py
@@ -47,7 +47,7 @@ class CategoryMembershipState(Constraint):
   _message_id_list = ['message_different_state']
 
   message_different_state = \
-      "${workflow_variable} for object ${membership_url} is ${current_state}" \
+      "${workflow_variable} for object ${membership_url} is ${current_state} " \
       "which is not in ${valid_state_list}"
 
   def checkConsistency(self, obj, fixit=0):