diff --git a/erpnext/accounts/doctype/accounts_settings/accounts_settings.py b/erpnext/accounts/doctype/accounts_settings/accounts_settings.py
index 24b0ec4..a3a32d5 100644
--- a/erpnext/accounts/doctype/accounts_settings/accounts_settings.py
+++ b/erpnext/accounts/doctype/accounts_settings/accounts_settings.py
@@ -40,6 +40,7 @@
 		
 		for doctype in ["Sales Invoice Item", "Purchase Invoice Item"]:
 			make_property_setter(doctype, "discount_account", "hidden", not(enable_discount_accounting), "Check", validate_fields_for_doctype=False)
+			make_property_setter(doctype, "discount_account", "mandatory", enable_discount_accounting, "Check", validate_fields_for_doctype=False)
 
 		for doctype in ["Sales Invoice", "Purchase Invoice"]:
 			make_property_setter(doctype, "additional_discount_account", "hidden", not(enable_discount_accounting), "Check", validate_fields_for_doctype=False)