diff --git a/adapters/outbound/util.go b/adapters/outbound/util.go
index 22b2d95..4fdbe00 100644
--- a/adapters/outbound/util.go
+++ b/adapters/outbound/util.go
@@ -33,11 +33,12 @@ func urlToMetadata(rawURL string) (addr C.Metadata, err error) {
 
 	port := u.Port()
 	if port == "" {
-		if u.Scheme == "https" {
+		switch u.Scheme {
+		case "https":
 			port = "443"
-		} else if u.Scheme == "http" {
+		case "http":
 			port = "80"
-		} else {
+		default:
 			err = fmt.Errorf("%s scheme not Support", rawURL)
 			return
 		}
diff --git a/common/observable/observable_test.go b/common/observable/observable_test.go
index c3d178d..41ee272 100644
--- a/common/observable/observable_test.go
+++ b/common/observable/observable_test.go
@@ -28,7 +28,7 @@ func TestObservable(t *testing.T) {
 	}
 	count := 0
 	for range data {
-		count = count + 1
+		count++
 	}
 	if count != 5 {
 		t.Error("Revc number error")
@@ -46,7 +46,7 @@ func TestObservable_MutilSubscribe(t *testing.T) {
 	wg.Add(2)
 	waitCh := func(ch <-chan interface{}) {
 		for range ch {
-			count = count + 1
+			count++
 		}
 		wg.Done()
 	}
diff --git a/component/v2ray-plugin/mux.go b/component/v2ray-plugin/mux.go
index 7191331..6bff27b 100644
--- a/component/v2ray-plugin/mux.go
+++ b/component/v2ray-plugin/mux.go
@@ -52,7 +52,7 @@ func (m *Mux) Read(b []byte) (int, error) {
 		if err != nil {
 			return 0, err
 		}
-		m.remain = m.remain - n
+		m.remain -= n
 		return n, nil
 	}
 
diff --git a/dns/util.go b/dns/util.go
index e29ea1b..cb6a1c4 100644
--- a/dns/util.go
+++ b/dns/util.go
@@ -81,13 +81,14 @@ func (e EnhancedMode) String() string {
 
 func putMsgToCache(c *cache.Cache, key string, msg *D.Msg) {
 	var ttl time.Duration
-	if len(msg.Answer) != 0 {
+	switch {
+	case len(msg.Answer) != 0:
 		ttl = time.Duration(msg.Answer[0].Header().Ttl) * time.Second
-	} else if len(msg.Ns) != 0 {
+	case len(msg.Ns) != 0:
 		ttl = time.Duration(msg.Ns[0].Header().Ttl) * time.Second
-	} else if len(msg.Extra) != 0 {
+	case len(msg.Extra) != 0:
 		ttl = time.Duration(msg.Extra[0].Header().Ttl) * time.Second
-	} else {
+	default:
 		log.Debugln("[DNS] response msg error: %#v", msg)
 		return
 	}