diff --git a/odoo/addons/base/models/res_partner.py b/odoo/addons/base/models/res_partner.py
index f717f32f413..6a28f10151b 100644
--- a/odoo/addons/base/models/res_partner.py
+++ b/odoo/addons/base/models/res_partner.py
@@ -712,7 +712,7 @@ class Partner(models.Model):
                                vat=unaccent('res_partner.vat'),)
 
             where_clause_params += [search_name]*3  # for email / display_name, reference
-            where_clause_params += [re.sub('[^a-zA-Z0-9]+', '', search_name)]  # for vat
+            where_clause_params += [re.sub('[^a-zA-Z0-9]+', '', search_name) or None]  # for vat
             where_clause_params += [search_name]  # for order by
             if limit:
                 query += ' limit %s'