diff --git a/addons/sms/models/mail_notification.py b/addons/sms/models/mail_notification.py
index 5fdfc33f477..b203abec10d 100644
--- a/addons/sms/models/mail_notification.py
+++ b/addons/sms/models/mail_notification.py
@@ -9,7 +9,7 @@ class MailNotification(models.Model):
 
     notification_type = fields.Selection(selection_add=[
         ('sms', 'SMS')
-    ], ondelete={'sms': 'set default'})
+    ], ondelete={'sms': 'cascade'})
     sms_id = fields.Many2one('sms.sms', string='SMS', index='btree_not_null', ondelete='set null')
     sms_number = fields.Char('SMS Number')
     failure_type = fields.Selection(selection_add=[