diff --git a/erpnext/accounts/doctype/payment_request/payment_request.py b/erpnext/accounts/doctype/payment_request/payment_request.py
index 03bb72b..6a84a65 100644
--- a/erpnext/accounts/doctype/payment_request/payment_request.py
+++ b/erpnext/accounts/doctype/payment_request/payment_request.py
@@ -548,10 +548,14 @@
 
 	return doclist
 
-def validate_payment(doc, method=""):
-	if not frappe.db.has_column(doc.reference_doctype, 'status'):
+def validate_payment(doc, method=None):
+	if doc.reference_doctype != "Payment Request" or (
+		frappe.db.get_value(doc.reference_doctype, doc.reference_docname, 'status')
+		!= "Paid"
+	):
 		return
 
-	status = frappe.db.get_value(doc.reference_doctype, doc.reference_docname, 'status')
-	if status == 'Paid':
-		frappe.throw(_("The Payment Request {0} is already paid, cannot process payment twice").format(doc.reference_docname))
\ No newline at end of file
+	frappe.throw(
+		_("The Payment Request {0} is already paid, cannot process payment twice")
+		.format(doc.reference_docname)
+	)