diff --git a/erpnext/accounts/doctype/sales_invoice/sales_invoice.py b/erpnext/accounts/doctype/sales_invoice/sales_invoice.py
index cb65557..ae8e476 100644
--- a/erpnext/accounts/doctype/sales_invoice/sales_invoice.py
+++ b/erpnext/accounts/doctype/sales_invoice/sales_invoice.py
@@ -996,10 +996,10 @@
 			if entry.amount < 0:
 				frappe.throw(_("Row #{0} (Payment Table): Amount must be positive").format(entry.idx))
 
-	def verify_payment_amount_is_negative(self):			
+	def verify_payment_amount_is_negative(self):
 		for entry in self.payments:
-    			if entry.amount > 0:
-				frappe.throw(_("Row #{0} (Payment Table): Amount must be negative").format(entry.idx))				
+			if entry.amount > 0:
+			frappe.throw(_("Row #{0} (Payment Table): Amount must be negative").format(entry.idx))				
 
 	# collection of the loyalty points, create the ledger entry for that.
 	def make_loyalty_point_entry(self):