diff --git a/ext/custom-addons/dp_custom/models/res_partner.py b/ext/custom-addons/dp_custom/models/res_partner.py
index d5e93f3f..9479f283 100644
--- a/ext/custom-addons/dp_custom/models/res_partner.py
+++ b/ext/custom-addons/dp_custom/models/res_partner.py
@@ -237,6 +237,14 @@ class Partner(models.Model):
                 if response.status_code != 200:
                     raise ValidationError(_('Rabatt konnte nicht gesetzt werden.'))
 
+    @api.multi
+    def write(self, vals):
+        fields_to_check = ['ref', 'portal_id']
+        for field in fields_to_check:
+            if field in vals and vals[field] == '':
+                vals[field] = False
+        return super(Partner, self).write(vals)
+
 
 class PartnerSector(models.Model):
     _name = 'res.partner.sector'