diff --git a/core/modules/system/tests/modules/common_test/common_test.routing.yml b/core/modules/system/tests/modules/common_test/common_test.routing.yml
index f3ad504..455c22b 100644
--- a/core/modules/system/tests/modules/common_test/common_test.routing.yml
+++ b/core/modules/system/tests/modules/common_test/common_test.routing.yml
@@ -5,7 +5,7 @@ common_test_l_active_class:
   requirements:
     _access: 'TRUE'
 common_test_js_and_css_querystring:
-  pattern: 'common-test/query-string'
+  pattern: '/common-test/query-string'
   defaults:
     _title: 'Test querystring'
     _content: '\Drupal\common_test\Controller\CommonTestController::jsAndCssQuerystring'