diff --git a/bili-signature.py b/bili-signature.py
index 7624cb5..9f52861 100644
--- a/bili-signature.py
+++ b/bili-signature.py
@@ -6,6 +6,7 @@
 import requests
 from rpnpy import Calculator
 import signal
+from sys import exit
 from time import sleep
 
 VERSION = '2.0'