diff --git a/shadowsocks/common.py b/shadowsocks/common.py
index 9dd5f7c..ee14995 100644
--- a/shadowsocks/common.py
+++ b/shadowsocks/common.py
@@ -37,9 +37,11 @@ def sha1_hmac(secret, data):
 def onetimeauth_verify(_hash, data, key):
     return _hash == sha1_hmac(key, data)[:ONETIMEAUTH_BYTES]
 
+
 def onetimeauth_gen(data, key):
     return sha1_hmac(key, data)[:ONETIMEAUTH_BYTES]
 
+
 def compat_ord(s):
     if type(s) == int:
         return s
diff --git a/shadowsocks/udprelay.py b/shadowsocks/udprelay.py
index cbfaa31..6d29f63 100644
--- a/shadowsocks/udprelay.py
+++ b/shadowsocks/udprelay.py
@@ -184,7 +184,7 @@ class UDPRelay(object):
                     logging.warn('UDP one time auth header is too short')
                     return
                 _hash = data[-ONETIMEAUTH_BYTES:]
-                _data =  data[header_length: -ONETIMEAUTH_BYTES]
+                _data = data[header_length: -ONETIMEAUTH_BYTES]
                 _key = self._encryptor.decipher_iv + self._encryptor.key
                 if onetimeauth_verify(_hash, _data, _key) is False:
                     logging.warn('UDP one time auth fail')