diff --git a/core/modules/system/tests/modules/twig_theme_test/twig_theme_test.routing.yml b/core/modules/system/tests/modules/twig_theme_test/twig_theme_test.routing.yml
index 45fd972..affd96a 100644
--- a/core/modules/system/tests/modules/twig_theme_test/twig_theme_test.routing.yml
+++ b/core/modules/system/tests/modules/twig_theme_test/twig_theme_test.routing.yml
@@ -29,6 +29,6 @@ twig_theme_test_link_generator:
 twig_theme_test.registry_loader:
   path: '/twig-theme-test/registry-loader'
   defaults:
-    _content: '\Drupal\twig_theme_test\TwigThemeTestController::registryLoaderRender'
+    _controller: '\Drupal\twig_theme_test\TwigThemeTestController::registryLoaderRender'
   requirements:
     _access: 'TRUE'