diff --git a/server/conn_test.go b/server/conn_test.go
index f5be261c8d541..7beb523c85103 100644
--- a/server/conn_test.go
+++ b/server/conn_test.go
@@ -428,10 +428,11 @@ func (ts *ConnTestSuite) testDispatch(c *C, inputs []dispatchInput, capability u
 	var outBuffer bytes.Buffer
 	tidbdrv := NewTiDBDriver(ts.store)
 	cfg := config.NewConfig()
-	cfg.Port = 4005
+	cfg.Port = genPort()
 	cfg.Status.ReportStatus = false
 	server, err := NewServer(cfg, tidbdrv)
 	c.Assert(err, IsNil)
+	defer server.Close()
 
 	cc := &clientConn{
 		connectionID: 1,