diff --git a/core/modules/block/src/BlockForm.php b/core/modules/block/src/BlockForm.php
index 08d7508..248edf7 100644
--- a/core/modules/block/src/BlockForm.php
+++ b/core/modules/block/src/BlockForm.php
@@ -109,12 +109,6 @@ public static function create(ContainerInterface $container) {
   public function form(array $form, FormStateInterface $form_state) {
     $entity = $this->entity;
 
-    // Store theme settings in $form_state for use below.
-    if (!$theme = $entity->getTheme()) {
-      $theme = $this->config('system.theme')->get('default');
-    }
-    $form_state->set('block_theme', $theme);
-
     // Store the gathered contexts in the form state for other objects to use
     // during form building.
     $form_state->setTemporaryValue('gathered_contexts', $this->dispatcher->dispatch(BlockEvents::ADMINISTRATIVE_CONTEXT, new BlockContextEvent())->getContexts());
@@ -139,7 +133,7 @@ public function form(array $form, FormStateInterface $form_state) {
     );
 
     // Theme settings.
-    if ($entity->getTheme()) {
+    if ($theme = $entity->getTheme()) {
       $form['theme'] = array(
         '#type' => 'value',
         '#value' => $theme,
diff --git a/core/modules/system/src/Plugin/Block/SystemBrandingBlock.php b/core/modules/system/src/Plugin/Block/SystemBrandingBlock.php
index c5ebaa5..e0b110d 100644
--- a/core/modules/system/src/Plugin/Block/SystemBrandingBlock.php
+++ b/core/modules/system/src/Plugin/Block/SystemBrandingBlock.php
@@ -78,20 +78,15 @@ public function defaultConfiguration() {
    * {@inheritdoc}
    */
   public function blockForm($form, FormStateInterface $form_state) {
-    // Get the theme.
-    $theme = $form_state->get('block_theme');
-
     // Get permissions.
     $url_system_theme_settings = new Url('system.theme_settings');
-    $url_system_theme_settings_theme = new Url('system.theme_settings_theme', array('theme' => $theme));
 
-    if ($url_system_theme_settings->access() && $url_system_theme_settings_theme->access()) {
-      // Provide links to the Appearance Settings and Theme Settings pages
-      // if the user has access to administer themes.
-      $site_logo_description = $this->t('Defined on the <a href="@appearance">Appearance Settings</a> or <a href="@theme">Theme Settings</a> page.', array(
+    if ($url_system_theme_settings->access()) {
+      // Provide links to the Appearance Settings page if the user has access to
+      // administer themes.
+      $site_logo_description = $this->t('Defined on the <a href="@appearance">Appearance Settings</a> page.', [
         '@appearance' => $url_system_theme_settings->toString(),
-        '@theme' => $url_system_theme_settings_theme->toString(),
-      ));
+      ]);
     }
     else {
       // Explain that the user does not have access to the Appearance and Theme