diff --git a/addons/crm/models/crm_lead.py b/addons/crm/models/crm_lead.py
index a7f4ff77290..e9cf8f9d372 100644
--- a/addons/crm/models/crm_lead.py
+++ b/addons/crm/models/crm_lead.py
@@ -249,6 +249,7 @@ class Lead(models.Model):
         team_id = self.env['crm.team']._get_default_team_id(user_id=user_id)
         return {'team_id': team_id}
 
+    @api.constrains('user_id')
     @api.onchange('user_id')
     def _onchange_user_id(self):
         """ When changing the user, also set a team_id or restrict team id to the ones user_id is member of. """
diff --git a/addons/website_crm_partner_assign/models/crm_lead.py b/addons/website_crm_partner_assign/models/crm_lead.py
index 6556deeec70..f5d59edbd8c 100644
--- a/addons/website_crm_partner_assign/models/crm_lead.py
+++ b/addons/website_crm_partner_assign/models/crm_lead.py
@@ -47,8 +47,6 @@ class CrmLead(models.Model):
         for salesman_id, leads_ids in salesmans_leads.items():
             leads = self.browse(leads_ids)
             leads.write({'user_id': salesman_id})
-            for lead in leads:
-                lead._onchange_user_id()
 
     @api.multi
     def action_assign_partner(self):