diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..a2950e2
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,21 @@
+fmt:
+	gofumpt -l -w .
+	gofmt -s -w .
+	gci write -s "standard,prefix(github.com/sagernet/),default" .
+
+lint_install:
+	go install github.com/golangci/golangci-lint/cmd/golangci-lint@latest
+
+lint:
+	GOOS=linux golangci-lint run ./...
+	GOOS=windows golangci-lint run ./...
+	GOOS=darwin golangci-lint run ./...
+	GOOS=freebsd golangci-lint run ./...
+
+test:
+	go test -v .
+
+update:
+	git fetch
+	git reset FETCH_HEAD --hard
+	git clean -fdx
\ No newline at end of file
diff --git a/common/bufio/race.go b/common/bufio/race.go
new file mode 100644
index 0000000..576e987
--- /dev/null
+++ b/common/bufio/race.go
@@ -0,0 +1,36 @@
+package bufio
+
+import (
+	"io"
+	"sync"
+
+	"github.com/sagernet/sing/common/buf"
+	N "github.com/sagernet/sing/common/network"
+)
+
+type RaceWriter struct {
+	upstream N.ExtendedWriter
+	access   sync.Mutex
+}
+
+func NewRaceWriter(writer io.Writer) *RaceWriter {
+	return &RaceWriter{
+		upstream: NewExtendedWriter(writer),
+	}
+}
+
+func (w *RaceWriter) WriteBuffer(buffer *buf.Buffer) error {
+	w.access.Lock()
+	defer w.access.Unlock()
+	return w.upstream.WriteBuffer(buffer)
+}
+
+func (w *RaceWriter) Write(p []byte) (n int, err error) {
+	w.access.Lock()
+	defer w.access.Unlock()
+	return w.upstream.Write(p)
+}
+
+func (w *RaceWriter) Upstream() any {
+	return w.upstream
+}
diff --git a/format.go b/format.go
deleted file mode 100644
index 7b30b9a..0000000
--- a/format.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package box
-
-//go:generate go install -v mvdan.cc/gofumpt@latest
-//go:generate go install -v github.com/daixiang0/gci@v0.4.0
-//go:generate gofumpt -l -w .
-//go:generate gofmt -s -w .
-//go:generate gci write -s "standard,prefix(github.com/sagernet/),default" .