diff --git a/erpnext/controllers/buying_controller.py b/erpnext/controllers/buying_controller.py
index b0d1e34..48b82bd 100644
--- a/erpnext/controllers/buying_controller.py
+++ b/erpnext/controllers/buying_controller.py
@@ -460,7 +460,7 @@
 	def validate_items(self):
 		# validate items to see if they have is_purchase_item or is_subcontracted_item enabled
 
-		if self.is_subcontracted:
+		if hasattr(self, "is_subcontracted") and self.is_subcontracted == 'Yes':
 			validate_item_type(self, "is_sub_contracted_item", "subcontracted")
 		else:
 			validate_item_type(self, "is_purchase_item", "purchase")