diff --git a/external/github.com/lucas-clemente/sync-files.sh b/external/github.com/lucas-clemente/sync-files.sh
deleted file mode 100755
index 7fe6758f5..000000000
--- a/external/github.com/lucas-clemente/sync-files.sh
+++ /dev/null
@@ -1,12 +0,0 @@
-#!/bin/bash
-
-rsync -rv "$GOPATH/src/v2ray.com/core/external/github.com/lucas-clemente/quic-go/" "$GOPATH/src/v2ray.com/core/vendor/v2ray.com/core/external/github.com/lucas-clemente/quic-go/"
-find . -name "*_test.go" -delete
-rm -rf ./quic-go/\.*
-rm -rf ./quic-go/benchmark
-rm -rf ./quic-go/docs
-rm -rf ./quic-go/example
-rm -rf ./quic-go/h2quic
-rm -rf ./quic-go/integrationtests
-rm -rf ./quic-go/vendor/golang\.org/
-rm ./quic-go/vendor/vendor.json