diff --git a/core/modules/user/src/Tests/Migrate/d7/MigrateUserTest.php b/core/modules/user/src/Tests/Migrate/d7/MigrateUserTest.php
index 149672b..14e3bf7 100644
--- a/core/modules/user/src/Tests/Migrate/d7/MigrateUserTest.php
+++ b/core/modules/user/src/Tests/Migrate/d7/MigrateUserTest.php
@@ -76,6 +76,7 @@ protected function assertEntity($id, $label, $mail, $access, $login, $blocked, $
     // $user->getPreferredLangcode() might fallback to default language if the
     // user preferred language is not configured on the site. We just want to
     // test if the value was imported correctly.
+    $langcode = $langcode ?: \Drupal::config('system.site')->get('default_langcode');
     $this->assertIdentical($langcode, $user->langcode->value);
     $this->assertIdentical($langcode, $user->preferred_langcode->value);
     $this->assertIdentical($langcode, $user->preferred_admin_langcode->value);