diff --git a/addons/website_mail/models/mail_thread.py b/addons/website_mail/models/mail_thread.py
index d7f750872ca6d7e495336bba5d8770c8f022587e..d4a37924b7987d2e27e959755d2456f9d667d656 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 = {