diff --git a/shadowsocks-csharp/Encryption/Stream/StreamMbedTLSEncryptor.cs b/shadowsocks-csharp/Encryption/Stream/StreamMbedTLSEncryptor.cs
index 9010aa8f..210fcef7 100644
--- a/shadowsocks-csharp/Encryption/Stream/StreamMbedTLSEncryptor.cs
+++ b/shadowsocks-csharp/Encryption/Stream/StreamMbedTLSEncryptor.cs
@@ -61,7 +61,6 @@ namespace Shadowsocks.Encryption.Stream
             if (_method == "rc4-md5")
             {
                 byte[] temp = new byte[keyLen + ivLen];
-                realkey = new byte[keyLen];
                 Array.Copy(_key, 0, temp, 0, keyLen);
                 Array.Copy(iv, 0, temp, keyLen, ivLen);
                 realkey = MbedTLS.MD5(temp);
diff --git a/shadowsocks-csharp/Encryption/Stream/StreamOpenSSLEncryptor.cs b/shadowsocks-csharp/Encryption/Stream/StreamOpenSSLEncryptor.cs
index 9fb3b0da..5897e09b 100644
--- a/shadowsocks-csharp/Encryption/Stream/StreamOpenSSLEncryptor.cs
+++ b/shadowsocks-csharp/Encryption/Stream/StreamOpenSSLEncryptor.cs
@@ -72,7 +72,6 @@ namespace Shadowsocks.Encryption.Stream
             if (_method == "rc4-md5")
             {
                 byte[] temp = new byte[keyLen + ivLen];
-                realkey = new byte[keyLen];
                 Array.Copy(_key, 0, temp, 0, keyLen);
                 Array.Copy(iv, 0, temp, keyLen, ivLen);
                 realkey = MbedTLS.MD5(temp);