diff --git a/ext/custom-addons/dp_custom/models/sale.py b/ext/custom-addons/dp_custom/models/sale.py
index 166c7eec..09e5567d 100644
--- a/ext/custom-addons/dp_custom/models/sale.py
+++ b/ext/custom-addons/dp_custom/models/sale.py
@@ -106,7 +106,7 @@ class SaleOrder(models.Model):
     def _compute_dlv_date_warn(self):
         for record in self:
             record.delivery_date_warning = False
-            if record.desired_delivery_date > record.delivery_date:
+            if record.desired_delivery_date and record.delivery_date and record.desired_delivery_date > record.delivery_date:
                 record.delivery_date_warning = True
 
     @api.multi