.../tests/modules/twig_theme_test/src/TwigThemeTestController.php      | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/core/modules/system/tests/modules/twig_theme_test/src/TwigThemeTestController.php b/core/modules/system/tests/modules/twig_theme_test/src/TwigThemeTestController.php
index ff49bd6..f01e1e9 100644
--- a/core/modules/system/tests/modules/twig_theme_test/src/TwigThemeTestController.php
+++ b/core/modules/system/tests/modules/twig_theme_test/src/TwigThemeTestController.php
@@ -72,6 +72,9 @@ public function fileUrlRender() {
    * Menu callback for testing the Twig registry loader.
    */
   public function registryLoaderRender() {
+    // Mark this page as being uncacheable.
+    \Drupal::service('page_cache_kill_switch')->trigger();
+
     return array('#theme' => 'twig_registry_loader_test');
   }