diff --git a/.travis.yml b/.travis.yml
index 24b234b..1d716f2 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -15,7 +15,7 @@ script:
   - pep8 .
   - python tests/test.py -c tests/table.json
   - python tests/test.py -c tests/aes.json
-  - python tests/test.py -c tests/rc4-sha256.json
+  - python tests/test.py -c tests/rc4-md5.json
   - python tests/test.py -c tests/salsa20.json
   - python tests/test.py -c tests/server-multi-ports.json
   - python tests/test.py -c tests/server-multi-passwd.json
diff --git a/shadowsocks/encrypt.py b/shadowsocks/encrypt.py
index 3537d00..d144e64 100644
--- a/shadowsocks/encrypt.py
+++ b/shadowsocks/encrypt.py
@@ -27,7 +27,7 @@ import string
 import struct
 import logging
 import encrypt_salsa20
-import encrypt_rc4_sha256
+import encrypt_rc4_md5
 
 
 def random_string(length):
@@ -116,7 +116,7 @@ method_supported = {
     'idea-cfb': (16, 8),
     'rc2-cfb': (16, 8),
     'rc4': (16, 0),
-    'rc4-sha256': (32, 16),
+    'rc4-md5': (16, 16),
     'seed-cfb': (16, 16),
     'salsa20-ctr': (32, 8),
 }
@@ -160,8 +160,8 @@ class Encryptor(object):
                 self.cipher_iv = iv[:m[1]]
             if method == 'salsa20-ctr':
                 return encrypt_salsa20.Salsa20Cipher(method, key, iv, op)
-            elif method == 'rc4-sha256':
-                return encrypt_rc4_sha256.create_cipher(method, key, iv, op)
+            elif method == 'rc4-md5':
+                return encrypt_rc4_md5.create_cipher(method, key, iv, op)
             else:
                 import M2Crypto.EVP
                 return M2Crypto.EVP.Cipher(method.replace('-', '_'), key, iv,
@@ -223,8 +223,8 @@ def encrypt_all(password, method, op, data):
             data = data[iv_len:]
         if method == 'salsa20-ctr':
             cipher = encrypt_salsa20.Salsa20Cipher(method, key, iv, op)
-        elif method == 'rc4-sha256':
-            cipher = encrypt_rc4_sha256.create_cipher(method, key, iv, op)
+        elif method == 'rc4-md5':
+            cipher = encrypt_rc4_md5.create_cipher(method, key, iv, op)
         else:
             cipher = M2Crypto.EVP.Cipher(method.replace('-', '_'), key, iv,
                                          op, key_as_bytes=0, d='md5',
diff --git a/shadowsocks/encrypt_rc4_sha256.py b/shadowsocks/encrypt_rc4_md5.py
similarity index 92%
rename from shadowsocks/encrypt_rc4_sha256.py
rename to shadowsocks/encrypt_rc4_md5.py
index 968f3e2..f71bad3 100644
--- a/shadowsocks/encrypt_rc4_sha256.py
+++ b/shadowsocks/encrypt_rc4_md5.py
@@ -25,10 +25,11 @@ import hashlib
 
 def create_cipher(alg, key, iv, op, key_as_bytes=0, d=None, salt=None,
                   i=1, padding=1):
-    sha256 = hashlib.sha256()
-    sha256.update(key)
-    sha256.update(iv)
-    rc4_key = sha256.digest()
+    md5 = hashlib.md5()
+    md5.update(key)
+    md5.update(iv)
+    rc4_key = md5.digest()
+    print len(rc4_key)
 
     import M2Crypto.EVP
     return M2Crypto.EVP.Cipher('rc4', rc4_key, '', op, key_as_bytes=0,
diff --git a/tests/rc4-sha256.json b/tests/rc4-md5.json
similarity index 83%
rename from tests/rc4-sha256.json
rename to tests/rc4-md5.json
index 7119c09..26ba0df 100644
--- a/tests/rc4-sha256.json
+++ b/tests/rc4-md5.json
@@ -4,7 +4,7 @@
     "local_port":1081,
     "password":"aes_password",
     "timeout":60,
-    "method":"rc4-sha256",
+    "method":"rc4-md5",
     "local_address":"127.0.0.1",
     "fast_open":false
 }