diff --git a/pkg/server/service/proxy_websocket_test.go b/pkg/server/service/proxy_websocket_test.go
index 8b58cf94a..84e6a1aef 100644
--- a/pkg/server/service/proxy_websocket_test.go
+++ b/pkg/server/service/proxy_websocket_test.go
@@ -593,9 +593,11 @@ func TestWebSocketTransferTLSConfig(t *testing.T) {
 	require.NoError(t, err)
 	assert.Equal(t, "ok", resp)
 
-	http.DefaultTransport.(*http.Transport).TLSClientConfig = &tls.Config{InsecureSkipVerify: true}
+	// Don't alter default transport to prevent side effects on other tests.
+	defaultTransport := http.DefaultTransport.(*http.Transport).Clone()
+	defaultTransport.TLSClientConfig = &tls.Config{InsecureSkipVerify: true}
 
-	forwarderWithTLSConfigFromDefaultTransport, err := buildProxy(Bool(true), nil, http.DefaultTransport, nil)
+	forwarderWithTLSConfigFromDefaultTransport, err := buildProxy(Bool(true), nil, defaultTransport, nil)
 	require.NoError(t, err)
 
 	proxyWithTLSConfigFromDefaultTransport := createProxyWithForwarder(t, forwarderWithTLSConfigFromDefaultTransport, srv.URL)