diff --git a/core/lib/Drupal/Core/Routing/CurrentRouteMatch.php b/core/lib/Drupal/Core/Routing/CurrentRouteMatch.php
index 2f4c0dd..4b482ea 100644
--- a/core/lib/Drupal/Core/Routing/CurrentRouteMatch.php
+++ b/core/lib/Drupal/Core/Routing/CurrentRouteMatch.php
@@ -128,7 +128,7 @@ public function getMasterRouteMatch() {
   /**
    * {@inheritdoc}
    */
-  public function getParentRequest() {
+  public function getParentRouteMatch() {
     return $this->getRouteMatch($this->requestStack->getParentRequest());
   }
 
diff --git a/core/lib/Drupal/Core/Routing/StackedRouteMatchInterface.php b/core/lib/Drupal/Core/Routing/StackedRouteMatchInterface.php
index 6ef2724..fde0035 100644
--- a/core/lib/Drupal/Core/Routing/StackedRouteMatchInterface.php
+++ b/core/lib/Drupal/Core/Routing/StackedRouteMatchInterface.php
@@ -34,7 +34,7 @@ public function getMasterRouteMatch();
    * @return \Drupal\Core\Routing\RouteMatchInterface\NULL
    *   The parent route match or NULL, if it the master route match.
    */
-  public function getParentRequest();
+  public function getParentRouteMatch();
 
 }
 
diff --git a/core/modules/system/src/Tests/System/ThemeTest.php b/core/modules/system/src/Tests/System/ThemeTest.php
index 2b11265..aeb5a2b 100644
--- a/core/modules/system/src/Tests/System/ThemeTest.php
+++ b/core/modules/system/src/Tests/System/ThemeTest.php
@@ -209,6 +209,14 @@ function testAdministrationTheme() {
     $this->drupalGet('admin/config');
     $this->assertRaw('core/themes/seven', 'Administration theme used on an administration page.');
 
+    // Ensure that the admin theme is also visible on the 403 page.
+    $normal_user = $this->drupalCreateUser();
+    $this->drupalLogin($normal_user);
+    $this->drupalGet('admin/config');
+    $this->assertResponse(403);
+    $this->assertRaw('core/themes/seven', 'Administration theme used on an administration page.');
+    $this->drupalLogin($this->admin_user);
+
     $this->drupalGet('node/add');
     $this->assertRaw('core/themes/stark', 'Site default theme used on the add content page.');