diff --git a/core/lib/Drupal/Core/Access/AccessArgumentsResolverFactory.php b/core/lib/Drupal/Core/Access/AccessArgumentsResolverFactory.php
index 0b788b5..cdef380 100644
--- a/core/lib/Drupal/Core/Access/AccessArgumentsResolverFactory.php
+++ b/core/lib/Drupal/Core/Access/AccessArgumentsResolverFactory.php
@@ -21,15 +21,20 @@ class AccessArgumentsResolverFactory implements AccessArgumentsResolverFactoryIn
    * {@inheritdoc}
    */
   public function getArgumentsResolver(RouteMatchInterface $route_match, AccountInterface $account, Request $request = NULL) {
-    $upcasted_route_arguments = $route_match->getParameters()->all();
-    $raw_route_arguments = $route_match->getRawParameters()->all();
+    $route = $route_match->getRouteObject();
+
+    // Defaults for the parameters defined on the route object need to be added
+    // to the raw arguments.
+    $raw_route_arguments = $route_match->getRawParameters()->all() + $route->getDefaults();
 
-    // @todo Remove this once AccessManagerInterface::checkNamedRoute() is fixed
-    //   to not leak _raw_variables from the request being duplicated.
-    // @see https://drupal.org/node/2265939
-    $raw_route_arguments += $upcasted_route_arguments;
+    $upcasted_route_arguments = $route_match->getParameters()->all();
 
-    $wildcard_arguments = [$route_match->getRouteObject(), $route_match, $account];
+    // Parameters which are not defined on the route object, but still are
+    // essential for access checking are passed as wildcards to the argument
+    // resolver. An access-check method with a parameter of type Route,
+    // RouteMatchInterface, AccountInterface or Request will receive those
+    // arguments regardless of the parameter name.
+    $wildcard_arguments = [$route, $route_match, $account];
     if (isset($request)) {
       $wildcard_arguments[] = $request;
     }
diff --git a/core/lib/Drupal/Core/Access/AccessManager.php b/core/lib/Drupal/Core/Access/AccessManager.php
index 8eb564c..5b2f871 100644
--- a/core/lib/Drupal/Core/Access/AccessManager.php
+++ b/core/lib/Drupal/Core/Access/AccessManager.php
@@ -165,13 +165,11 @@ public function checkNamedRoute($route_name, array $parameters, AccountInterface
     try {
       $route = $this->routeProvider->getRouteByName($route_name, $parameters);
 
-      // Populate a new route match with both raw and converted parameters.
-      $parameters += $route->getDefaults();
-
-      // @todo: do we really need this? and why not ROUTE_NAME?
+      // ParamConverterManager relies on the route object being available
+      // from the parameters array.
       $parameters[RouteObjectInterface::ROUTE_OBJECT] = $route;
-
       $upcasted_parameters = $this->paramConverterManager->convert($parameters, new Request());
+
       $route_match = new RouteMatch($route_name, $route, $upcasted_parameters, $parameters);
       return $this->check($route_match, $account);
     }