diff --git a/upgrader_test.go b/upgrader_test.go
index 085a80f1..956e061e 100644
--- a/upgrader_test.go
+++ b/upgrader_test.go
@@ -5,13 +5,23 @@ import (
 	"bytes"
 	"crypto/tls"
 	"errors"
+	"fmt"
 	"github.com/stretchr/testify/assert"
 	"net"
 	"net/http"
+	"strconv"
 	"sync"
+	"sync/atomic"
 	"testing"
 )
 
+var _port = int64(9999)
+
+func nextPort() string {
+	port := atomic.AddInt64(&_port, 1)
+	return strconv.Itoa(int(port))
+}
+
 func newHttpWriter() *httpWriter {
 	server, client := net.Pipe()
 	var r = bytes.NewBuffer(nil)
@@ -209,44 +219,50 @@ func TestNewServer(t *testing.T) {
 	var as = assert.New(t)
 
 	t.Run("ok", func(t *testing.T) {
+		var addr = ":" + nextPort()
 		var server = NewServer(new(BuiltinEventHandler), nil)
-		go server.Run(":12345")
+		go server.Run(addr)
 		_, _, err := NewClient(new(BuiltinEventHandler), &ClientOption{
-			Addr: "ws://localhost:12345",
+			Addr: "ws://localhost" + addr,
 		})
 		as.NoError(err)
 	})
 
 	t.Run("tls", func(t *testing.T) {
+		var addr = ":" + nextPort()
 		var server = NewServer(new(BuiltinEventHandler), nil)
-		go server.RunTLS(":12346", "", "")
+		go server.RunTLS(addr, "", "")
 	})
 
 	t.Run("fail 1", func(t *testing.T) {
+		var addr = ":" + nextPort()
 		var wg = sync.WaitGroup{}
 		wg.Add(1)
 		var server = NewServer(new(BuiltinEventHandler), nil)
 		server.OnError = func(conn net.Conn, err error) {
 			wg.Done()
 		}
-		go server.Run(":12347")
-		client, err := net.Dial("tcp", "localhost:12347")
+		go server.Run(addr)
+		client, err := net.Dial("tcp", "localhost"+addr)
 		as.NoError(err)
-		client.Write([]byte("POST ws://localhost:12347 HTTP/1.1\r\n\r\n"))
+		var payload = fmt.Sprintf("POST ws://localhost%s HTTP/1.1\r\n\r\n", addr)
+		client.Write([]byte(payload))
 		wg.Wait()
 	})
 
 	t.Run("fail 2", func(t *testing.T) {
+		var addr = ":" + nextPort()
 		var wg = sync.WaitGroup{}
 		wg.Add(1)
 		var server = NewServer(new(BuiltinEventHandler), nil)
 		server.OnError = func(conn net.Conn, err error) {
 			wg.Done()
 		}
-		go server.Run(":12347")
-		client, err := net.Dial("tcp", "localhost:12347")
+		go server.Run(addr)
+		client, err := net.Dial("tcp", "localhost"+addr)
 		as.NoError(err)
-		client.Write([]byte("GET ws://localhost:12347 HTTP/1.1 GWS\r\n\r\n"))
+		var payload = fmt.Sprintf("GET ws://localhost%s HTTP/1.1 GWS\r\n\r\n", addr)
+		client.Write([]byte(payload))
 		wg.Wait()
 	})
 }