diff --git a/addons/website_sale/models/res_partner.py b/addons/website_sale/models/res_partner.py
index 6755a4b6a54..77fc633c9c8 100644
--- a/addons/website_sale/models/res_partner.py
+++ b/addons/website_sale/models/res_partner.py
@@ -7,4 +7,4 @@ from odoo import models, fields
 class ResPartner(models.Model):
     _inherit = 'res.partner'
 
-    last_website_so_id = fields.Many2one('sale.order', string='Last Online Sales Order')
+    last_website_so_id = fields.Many2one('sale.order', string='Last Online Sales Order', copy=False)