diff --git a/erpnext/accounts/doctype/payment_entry/payment_entry.js b/erpnext/accounts/doctype/payment_entry/payment_entry.js
index 6ecd8fa..ce0cb50 100644
--- a/erpnext/accounts/doctype/payment_entry/payment_entry.js
+++ b/erpnext/accounts/doctype/payment_entry/payment_entry.js
@@ -406,7 +406,10 @@
 
 		if(!frm.doc.paid_amount && frm.doc.paid_from_account_currency == frm.doc.paid_to_account_currency) {
 			frm.set_value("paid_amount", frm.doc.received_amount);
-			frm.set_value("source_exchange_rate", frm.doc.target_exchange_rate);
+
+			if(frm.doc.target_exchange_rate) {
+				frm.set_value("source_exchange_rate", frm.doc.target_exchange_rate);
+			}
 			frm.set_value("base_paid_amount", frm.doc.base_received_amount);
 		}
 
@@ -426,7 +429,10 @@
 				(frm.doc.paid_from_account_currency == frm.doc.paid_to_account_currency)) {
 			
 			frm.set_value("received_amount", frm.doc.paid_amount);
-			frm.set_value("target_exchange_rate", frm.doc.source_exchange_rate);
+
+			if(frm.doc.source_exchange_rate) {
+				frm.set_value("target_exchange_rate", frm.doc.source_exchange_rate);
+			}
 			frm.set_value("base_received_amount", frm.doc.base_paid_amount);
 		}