core/modules/rest/rest.services.yml                |  4 ---
 .../src/EventSubscriber/RestRouteSubscriber.php    | 40 ----------------------
 .../src/EventSubscriber/AdminRouteSubscriber.php   | 20 +++++++++--
 3 files changed, 17 insertions(+), 47 deletions(-)

diff --git a/core/modules/rest/rest.services.yml b/core/modules/rest/rest.services.yml
index ebed915..869eb19 100644
--- a/core/modules/rest/rest.services.yml
+++ b/core/modules/rest/rest.services.yml
@@ -31,7 +31,3 @@ services:
     arguments: ['@router.builder']
     tags:
       - { name: event_subscriber }
-  rest.route_subscriber:
-    class: Drupal\rest\EventSubscriber\RestRouteSubscriber
-    tags:
-      - { name: event_subscriber }
diff --git a/core/modules/rest/src/EventSubscriber/RestRouteSubscriber.php b/core/modules/rest/src/EventSubscriber/RestRouteSubscriber.php
deleted file mode 100644
index bd81370..0000000
--- a/core/modules/rest/src/EventSubscriber/RestRouteSubscriber.php
+++ /dev/null
@@ -1,40 +0,0 @@
-<?php
-
-namespace Drupal\rest\EventSubscriber;
-
-use Drupal\Core\Routing\RouteSubscriberBase;
-use Drupal\Core\Routing\RoutingEvents;
-use Symfony\Component\Routing\RouteCollection;
-
-/**
- * Performs certain alterations to REST routes.
- */
-class RestRouteSubscriber extends RouteSubscriberBase {
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function alterRoutes(RouteCollection $collection) {
-    foreach ($collection->all() as $name => $route) {
-      // Removes the '_admin_route' route option from each REST route that had
-      // it added by \Drupal\system\EventSubscriber\AdminRouteSubscriber.
-      if (strpos($name, 'rest.') === 0 && $route->hasOption('_admin_route')) {
-        $route->setOption('_admin_route', FALSE);
-      }
-    }
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public static function getSubscribedEvents() {
-    $events = parent::getSubscribedEvents();
-
-    // Use a very low priority to run as late as possible. Especially use a
-    // lower priority than \Drupal\system\EventSubscriber\AdminRouteSubscriber.
-    $events[RoutingEvents::ALTER] = ['onAlterRoutes', -1000];
-
-    return $events;
-  }
-
-}
diff --git a/core/modules/system/src/EventSubscriber/AdminRouteSubscriber.php b/core/modules/system/src/EventSubscriber/AdminRouteSubscriber.php
index b83fe7e..ac2a47f 100644
--- a/core/modules/system/src/EventSubscriber/AdminRouteSubscriber.php
+++ b/core/modules/system/src/EventSubscriber/AdminRouteSubscriber.php
@@ -4,10 +4,11 @@
 
 use Drupal\Core\Routing\RouteSubscriberBase;
 use Drupal\Core\Routing\RoutingEvents;
+use Symfony\Component\Routing\Route;
 use Symfony\Component\Routing\RouteCollection;
 
 /**
- * Adds the _admin_route option to each admin route.
+ * Adds the _admin_route option to each admin HTML route.
  */
 class AdminRouteSubscriber extends RouteSubscriberBase {
 
@@ -15,14 +16,27 @@ class AdminRouteSubscriber extends RouteSubscriberBase {
    * {@inheritdoc}
    */
   protected function alterRoutes(RouteCollection $collection) {
-    foreach ($collection->all() as $route) {
-      if (strpos($route->getPath(), '/admin') === 0 && !$route->hasOption('_admin_route')) {
+    foreach ($collection->all() as $name => $route) {
+      if (strpos($route->getPath(), '/admin') === 0 && !$route->hasOption('_admin_route') && static::isHtmlRoute($route)) {
         $route->setOption('_admin_route', TRUE);
       }
     }
   }
 
   /**
+   * Whether the given route is a HTML route.
+   *
+   * @param \Symfony\Component\Routing\Route $route
+   *   The route to inspect.
+   *
+   * @return bool
+   *   Whether the given route is a HTML route.
+   */
+  protected static function isHtmlRoute(Route $route) {
+    return !$route->hasRequirement('_format') || in_array('html', explode('|', $route->getRequirement('_format')), TRUE);
+  }
+
+  /**
    * {@inheritdoc}
    */
   public static function getSubscribedEvents() {