diff --git a/shadowsocks/encrypt.py b/shadowsocks/encrypt.py
index 57540bc..9609f89 100644
--- a/shadowsocks/encrypt.py
+++ b/shadowsocks/encrypt.py
@@ -75,7 +75,8 @@ def EVP_BytesToKey(password, key_len, iv_len):
 class Encryptor(object):
     def __init__(self, key, method):
         self.key = key
-        self.method = common.to_str(method)
+        method = common.to_str(method)
+        self.method = method
         self.iv = None
         self.iv_sent = False
         self.cipher_iv = b''