diff --git a/erpnext/manufacturing/doctype/production_order/production_order.py b/erpnext/manufacturing/doctype/production_order/production_order.py
index 1486d2a..99a248b 100644
--- a/erpnext/manufacturing/doctype/production_order/production_order.py
+++ b/erpnext/manufacturing/doctype/production_order/production_order.py
@@ -47,7 +47,7 @@
 
 				self.validate_production_order_against_so()
 			else:
-				frappe.throw(_("Sales Order {0} is not valid") % self.sales_order)
+				frappe.throw(_("Sales Order {0} is not valid").format(self.sales_order))
 
 	def validate_warehouse(self):
 		from erpnext.stock.utils import validate_warehouse_company