diff --git a/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Plugin/migrate/process/d6/BlockTheme.php b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Plugin/migrate/process/d6/BlockTheme.php
index bad88ef..cf77da5 100644
--- a/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Plugin/migrate/process/d6/BlockTheme.php
+++ b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Plugin/migrate/process/d6/BlockTheme.php
@@ -41,9 +41,10 @@ class BlockTheme extends ProcessPluginBase implements ContainerFactoryPluginInte
    * @param \Drupal\Core\Config\Config $config
    *   The configuration factory object.
    */
-  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, Config $config) {
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, Config $config, array $themes) {
     parent::__construct($configuration, $plugin_id, $plugin_definition, $migration);
     $this->config = $config;
+    $this->themes = $themes;
   }
 
   /**
@@ -55,7 +56,8 @@ public static function create(ContainerInterface $container, array $configuratio
       $plugin_id,
       $plugin_definition,
       $migration,
-      $container->get('config.factory')->get('system.theme')
+      $container->get('config.factory')->get('system.theme'),
+      $container->get('theme_handler')->listInfo()
     );
   }
 
@@ -67,15 +69,15 @@ public static function create(ContainerInterface $container, array $configuratio
   public function transform($value, MigrateExecutable $migrate_executable, Row $row, $destination_property) {
     list($theme, $d6_default_theme, $d6_admin_theme) = $value;
 
-    $d8_default_theme = $this->config->get('default');
-    $d8_admin_theme = $this->config->get('admin');
-
     // If the source theme exists on the destination, we're good.
-    $themes = \Drupal::service('theme_handler')->listInfo();
-    if (isset($themes[$theme])) {
+    if (isset($this->themes[$theme])) {
       return $theme;
     }
 
+    // Get the default destination themes.
+    $d8_default_theme = $this->config->get('default');
+    $d8_admin_theme = $this->config->get('admin');
+
     // If the source block is assigned to a region in the source default theme, then assign it to the destination default theme.
     if (strtolower($theme) == strtolower($d6_default_theme)) {
       return $d8_default_theme;