diff --git a/core/rebuild.php b/core/rebuild.php
index 024b4e6..9ecf17d 100644
--- a/core/rebuild.php
+++ b/core/rebuild.php
@@ -10,13 +10,14 @@
 
 use Drupal\Component\PhpStorage\PhpStorageFactory;
 use Drupal\Core\Cache\CacheFactory;
+use Drupal\Component\Utility\Crypt;
 
 // Change the directory to the Drupal root.
 chdir('..');
 
 require_once dirname(__DIR__) . '/core/includes/bootstrap.inc';
 drupal_bootstrap(DRUPAL_BOOTSTRAP_CONFIGURATION);
-if (isset($_GET['token']) && isset($_GET['timestamp']) && REQUEST_TIME - $_GET['timestamp'] < 300 && $_GET['token'] === drupal_hmac_base64($_GET['timestamp'], $GLOBALS['drupal_hash_salt'])) {
+if (isset($_GET['token']) && isset($_GET['timestamp']) && REQUEST_TIME - $_GET['timestamp'] < 300 && $_GET['token'] === ($_GET['timestamp'], $GLOBALS['drupal_hash_salt'])) {
   // drupal_bootstrap(DRUPAL_BOOTSTRAP_KERNEL) will build a new kernel.
   PhpStorageFactory::get('service_container')->deleteAll();
   PhpStorageFactory::get('twig')->deleteAll();
diff --git a/core/scripts/rebuild_token_calculator.sh b/core/scripts/rebuild_token_calculator.sh
old mode 100644
new mode 100755
index 92a02aa..2369cd8
--- a/core/scripts/rebuild_token_calculator.sh
+++ b/core/scripts/rebuild_token_calculator.sh
@@ -6,12 +6,15 @@
  * Command line token calculator for rebuild.php.
  */
 
+require_once __DIR__ . '/../vendor/autoload.php';
+
+use Drupal\Component\Utility\Crypt;
+
 if (PHP_SAPI !== 'cli') {
   exit;
 }
-$core = dirname(__DIR__);
-include dirname($core) . '/sites/default/settings.php';
-include $core . '/includes/bootstrap.inc';
+
 $timestamp = time();
-$token = drupal_hmac_base64($timestamp, $drupal_hash_salt);
+$token = Crypt::hmacBase64($timestamp, $drupal_hash_salt);
+
 print "timestamp=$timestamp&token=$token\n";