diff --git a/core/lib/Drupal/Core/Access/AccessArgumentsResolverFactory.php b/core/lib/Drupal/Core/Access/AccessArgumentsResolverFactory.php
index ddb3a51..cdef380 100644
--- a/core/lib/Drupal/Core/Access/AccessArgumentsResolverFactory.php
+++ b/core/lib/Drupal/Core/Access/AccessArgumentsResolverFactory.php
@@ -22,7 +22,11 @@ class AccessArgumentsResolverFactory implements AccessArgumentsResolverFactoryIn
    */
   public function getArgumentsResolver(RouteMatchInterface $route_match, AccountInterface $account, Request $request = NULL) {
     $route = $route_match->getRouteObject();
-    $raw_route_arguments = $route_match->getRawParameters()->all();
+
+    // 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();
+
     $upcasted_route_arguments = $route_match->getParameters()->all();
 
     // Parameters which are not defined on the route object, but still are