diff --git a/core/modules/system/src/Controller/SystemController.php b/core/modules/system/src/Controller/SystemController.php
index 41e351faf8..ebe4996298 100644
--- a/core/modules/system/src/Controller/SystemController.php
+++ b/core/modules/system/src/Controller/SystemController.php
@@ -330,7 +330,9 @@ public function themesPage() {
               'attributes' => ['title' => $this->t('Set @theme as default theme', ['@theme' => $theme->info['name']])],
             ];
           }
-          $admin_theme_options[$theme->getName()] = $theme->info['name'] . ($theme->is_experimental ? ' (' . t('Experimental') . ')' : '');
+          if (isset($theme->info['admin theme']) && $theme->info['admin theme'] == TRUE) {
+            $admin_theme_options[$theme->getName()] = $theme->info['name'] . ($theme->is_experimental ? ' (' . t('Experimental') . ')' : '');
+          }
         }
         else {
           $theme->operations[] = [
diff --git a/core/modules/system/src/Form/ThemeAdminForm.php b/core/modules/system/src/Form/ThemeAdminForm.php
index 1951f54829..8a82b906e6 100644
--- a/core/modules/system/src/Form/ThemeAdminForm.php
+++ b/core/modules/system/src/Form/ThemeAdminForm.php
@@ -38,7 +38,7 @@ public function buildForm(array $form, FormStateInterface $form_state, array $th
     ];
     $form['admin_theme']['admin_theme'] = [
       '#type' => 'select',
-      '#options' => ['' => $this->t('Default theme')] + $theme_options,
+      '#options' => $theme_options,
       '#title' => $this->t('Administration theme'),
       '#description' => $this->t('Choose "Default theme" to always use the same theme as the rest of the site.'),
       '#default_value' => $this->config('system.theme')->get('admin'),
diff --git a/core/themes/claro/claro.info.yml b/core/themes/claro/claro.info.yml
index 07be922f74..baf0175f88 100644
--- a/core/themes/claro/claro.info.yml
+++ b/core/themes/claro/claro.info.yml
@@ -18,6 +18,7 @@ alt text: 'Screenshot of Claro, Drupal administration theme.'
 package: Core
 version: VERSION
 experimental: true
+admin theme: true
 libraries:
   - core/drupal.message
   - core/normalize
diff --git a/core/themes/seven/seven.info.yml b/core/themes/seven/seven.info.yml
index f02a6f0a86..1df22aa033 100644
--- a/core/themes/seven/seven.info.yml
+++ b/core/themes/seven/seven.info.yml
@@ -18,6 +18,7 @@ description: 'The default administration theme for Drupal 8 was designed with cl
 alt text: 'Default administration theme for Drupal 8 with simple blocks and clean lines.'
 package: Core
 version: VERSION
+admin theme: true
 libraries:
   - seven/classy.messages
   - core/normalize