diff --git a/addons/website_mail/models/mail_thread.py b/addons/website_mail/models/mail_thread.py
index d7f750872ca..d4a37924b79 100644
--- a/addons/website_mail/models/mail_thread.py
+++ b/addons/website_mail/models/mail_thread.py
@@ -22,7 +22,7 @@
 from openerp.osv import osv, fields
 
 # TODO for trunk, remove me
-class MailThread(osv.Model):
+class MailThread(osv.AbstractModel):
     _inherit = 'mail.thread'
 
     _columns = {