diff --git a/erpnext/accounts/doctype/payment_entry/payment_entry.py b/erpnext/accounts/doctype/payment_entry/payment_entry.py
index e0ec76f..443c8fb 100644
--- a/erpnext/accounts/doctype/payment_entry/payment_entry.py
+++ b/erpnext/accounts/doctype/payment_entry/payment_entry.py
@@ -749,7 +749,7 @@
 
 @frappe.whitelist()
 def get_reference_details(reference_doctype, reference_name, party_account_currency):
-	total_amount = outstanding_amount = exchange_rate = None
+	total_amount = outstanding_amount = exchange_rate = bill_no = None
 	ref_doc = frappe.get_doc(reference_doctype, reference_name)
 	company_currency = ref_doc.get("company_currency") or erpnext.get_company_currency(ref_doc.company)