diff --git a/addons/mail/mail_thread.py b/addons/mail/mail_thread.py
index c6ac11731cd..8aaed056559 100644
--- a/addons/mail/mail_thread.py
+++ b/addons/mail/mail_thread.py
@@ -73,7 +73,8 @@ class mail_thread(osv.osv):
     # OpenSocial: message_ids_social is a dummy field that should not be used
     _columns = {
         'message_ids_social': fields.function(_get_message_ids, method=True,
-                        type='one2many', obj='mail.message', string='Temp messages'),
+                        type='one2many', obj='mail.message', string='Temp messages',
+                        _fields_id = 'res_id'),
     }
 
     #------------------------------------------------------