diff --git a/core/lib/Drupal/Core/Theme/AjaxBasePageNegotiator.php b/core/lib/Drupal/Core/Theme/AjaxBasePageNegotiator.php
index 261cedf..59b4f53 100644
--- a/core/lib/Drupal/Core/Theme/AjaxBasePageNegotiator.php
+++ b/core/lib/Drupal/Core/Theme/AjaxBasePageNegotiator.php
@@ -67,10 +67,7 @@ public function __construct(CsrfTokenGenerator $token_generator, ConfigFactoryIn
    * {@inheritdoc}
    */
   public function applies(RouteMatchInterface $route_match) {
-    // Check whether the route was configured to use the base page theme.
-    return ($route = $route_match->getRouteObject())
-      && $route->hasOption('_theme')
-      && $route->getOption('_theme') == 'ajax_base_page';
+    return FALSE;
   }
 
   /**