diff --git a/core/lib/Drupal/Core/Access/AccessInterface.php b/core/lib/Drupal/Core/Access/AccessInterface.php
index d37a51f..8f85de3 100644
--- a/core/lib/Drupal/Core/Access/AccessInterface.php
+++ b/core/lib/Drupal/Core/Access/AccessInterface.php
@@ -20,14 +20,14 @@
    *
    * A checker should return this value to indicate that it grants access.
    */
-  const ALLOW = TRUE;
+  const ALLOW = 'ALLOW';
 
   /**
    * Deny access.
    *
    * A checker should return this value to indicate it does not grant access.
    */
-  const DENY = NULL;
+  const DENY = 'DENY';
 
   /**
    * Block access.
@@ -36,6 +36,6 @@
    * block access, regardless of any other access checkers. Most checkers
    * should prefer DENY.
    */
-  const KILL = FALSE;
+  const KILL = 'KILL';
 
 }
diff --git a/core/tests/Drupal/Tests/Core/Access/AccessManagerTest.php b/core/tests/Drupal/Tests/Core/Access/AccessManagerTest.php
index 879fcbc..740191c 100644
--- a/core/tests/Drupal/Tests/Core/Access/AccessManagerTest.php
+++ b/core/tests/Drupal/Tests/Core/Access/AccessManagerTest.php
@@ -11,10 +11,8 @@
 use Drupal\Core\Routing\Access\AccessInterface;
 use Drupal\Core\Access\AccessManager;
 use Drupal\Core\Access\DefaultAccessCheck;
-use Drupal\system\Tests\Routing\MockRouteProvider;
 use Drupal\Tests\UnitTestCase;
 use Drupal\router_test\Access\DefinedTestAccessCheck;
-use Symfony\Cmf\Component\Routing\RouteObjectInterface;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\Routing\Exception\RouteNotFoundException;