diff --git a/unipay/providers/transfer.py b/unipay/providers/transfer.py
index 549d0c4..08050b8 100644
--- a/unipay/providers/transfer.py
+++ b/unipay/providers/transfer.py
@@ -102,7 +102,7 @@ class TransferPay(Gateway):
 	
 	def gen_mailcode(self):
 		c = '1'
-		for range(6):
+		for i in range(6):
 			c += randint(0,9)
 		return c