diff --git a/selling/doctype/sales_order/sales_order.py b/selling/doctype/sales_order/sales_order.py
index ec2406f..8e3ed70 100644
--- a/selling/doctype/sales_order/sales_order.py
+++ b/selling/doctype/sales_order/sales_order.py
@@ -152,7 +152,8 @@
 	def validate_warehouse_user(self):
 		from stock.utils import validate_warehouse_user
 		
-		warehouses = list(set([d.reserved_warehouse for d in self.doclist.get({"doctype": self.tname})]))
+		warehouses = list(set([d.reserved_warehouse for d in 
+			self.doclist.get({"doctype": self.tname}) if d.reserved_warehouse]))
 				
 		for w in warehouses:
 			validate_warehouse_user(w)