diff --git a/transport/socks4/socks4.go b/transport/socks4/socks4.go
index c6b2f2db..c06bea20 100644
--- a/transport/socks4/socks4.go
+++ b/transport/socks4/socks4.go
@@ -91,6 +91,7 @@ func ServerHandshake(rw io.ReadWriter, authenticator auth.Authenticator) (addr s
 		code = RequestGranted
 	} else {
 		code = RequestIdentdMismatched
+		err = ErrRequestIdentdMismatched
 	}
 
 	var reply [8]byte
@@ -99,7 +100,10 @@ func ServerHandshake(rw io.ReadWriter, authenticator auth.Authenticator) (addr s
 	copy(reply[4:8], dstIP)
 	copy(reply[2:4], dstPort)
 
-	_, err = rw.Write(reply[:])
+	_, wErr := rw.Write(reply[:])
+	if err == nil {
+		err = wErr
+	}
 	return
 }