diff --git a/component/http/http.go b/component/http/http.go
index 2d709f54..d50eeb91 100644
--- a/component/http/http.go
+++ b/component/http/http.go
@@ -50,7 +50,7 @@ func HttpRequest(ctx context.Context, url, method string, header map[string][]st
 		}
 	}
 
-	if _, ok := req.Header["User-Agent"]; !ok {
+	if req.Header.Get("User-Agent") == "" {
 		req.Header.Set("User-Agent", UA())
 	}
 
diff --git a/transport/gun/gun.go b/transport/gun/gun.go
index 7ca1f061..4d924530 100644
--- a/transport/gun/gun.go
+++ b/transport/gun/gun.go
@@ -351,7 +351,7 @@ func StreamGunWithTransport(transport *TransportWrap, cfg *Config) (net.Conn, er
 
 	header := defaultHeader.Clone()
 	if cfg.UserAgent != "" {
-		header["user-agent"] = []string{cfg.UserAgent}
+		header.Set("User-Agent", cfg.UserAgent)
 	}
 
 	request := &http.Request{