diff --git a/shadowsocks/encrypt.go b/shadowsocks/encrypt.go
index ebf4f34..5eb771a 100644
--- a/shadowsocks/encrypt.go
+++ b/shadowsocks/encrypt.go
@@ -19,10 +19,10 @@ func md5sum(d []byte) []byte {
 	return h.Sum(nil)
 }
 
-func evpBytesToKey(password string, keyLen, ivLen int) (key, iv []byte) {
+func evpBytesToKey(password string, keyLen int) (key []byte) {
 	const md5Len = 16
 
-	cnt := (keyLen+ivLen-1)/md5Len + 1
+	cnt := (keyLen-1)/md5Len + 1
 	m := make([]byte, cnt*md5Len)
 	copy(m, md5sum([]byte(password)))
 
@@ -36,7 +36,7 @@ func evpBytesToKey(password string, keyLen, ivLen int) (key, iv []byte) {
 		copy(d[md5Len:], password)
 		copy(m[start:], md5sum(d))
 	}
-	return m[:keyLen], m[keyLen : keyLen+ivLen]
+	return m[:keyLen]
 }
 
 func (tbl tableCipher) XORKeyStream(dst, src []byte) {
diff --git a/shadowsocks/encrypt_test.go b/shadowsocks/encrypt_test.go
index 78cd0a2..ad47f70 100644
--- a/shadowsocks/encrypt_test.go
+++ b/shadowsocks/encrypt_test.go
@@ -78,11 +78,11 @@ func TestRC4Cipher(t *testing.T) {
 func TestEvpBytesToKey(t *testing.T) {
 	key, iv := evpBytesToKey("foobar", 32, 16)
 	keyTarget := []byte{0x38, 0x58, 0xf6, 0x22, 0x30, 0xac, 0x3c, 0x91, 0x5f, 0x30, 0x0c, 0x66, 0x43, 0x12, 0xc6, 0x3f, 0x56, 0x83, 0x78, 0x52, 0x96, 0x14, 0xd2, 0x2d, 0xdb, 0x49, 0x23, 0x7d, 0x2f, 0x60, 0xbf, 0xdf}
-	ivTarget := []byte{0x0e, 0xbf, 0x58, 0x78, 0xe8, 0x2a, 0xf7, 0xda, 0x61, 0x8e, 0xd5, 0x6f, 0xc6, 0x7d, 0x4a, 0xb7}
+	// ivTarget := []byte{0x0e, 0xbf, 0x58, 0x78, 0xe8, 0x2a, 0xf7, 0xda, 0x61, 0x8e, 0xd5, 0x6f, 0xc6, 0x7d, 0x4a, 0xb7}
 	if !reflect.DeepEqual(key, keyTarget) {
 		t.Errorf("key not correct\n\texpect: %v\n\tgot:   %v\n", keyTarget, key)
 	}
-	if !reflect.DeepEqual(iv, ivTarget) {
-		t.Errorf("iv not correct\n\texpect: %v\n\tgot:   %v\n", ivTarget, iv)
-	}
+	// if !reflect.DeepEqual(iv, ivTarget) {
+	// 	t.Errorf("iv not correct\n\texpect: %v\n\tgot:   %v\n", ivTarget, iv)
+	// }
 }