diff --git a/erpnext/controllers/selling_controller.py b/erpnext/controllers/selling_controller.py
index e758dd1..86d8837 100644
--- a/erpnext/controllers/selling_controller.py
+++ b/erpnext/controllers/selling_controller.py
@@ -339,7 +339,7 @@
 			reserved_warehouse = ""
 			reserved_qty_for_main_item = 0
 
-			if not d.qty:
+			if d.qty is None:
 				frappe.throw(_("Row {0}: Qty is mandatory").format(d.idx))
 
 			if self.doctype == "Sales Order":