diff --git a/core/includes/update.inc b/core/includes/update.inc
index 5aff2bc..f3c8db0 100644
--- a/core/includes/update.inc
+++ b/core/includes/update.inc
@@ -86,6 +86,7 @@ function update_prepare_d8_bootstrap() {
   // Allow the database system to work even if the registry has not been
   // created yet.
   include_once DRUPAL_ROOT . '/core/includes/install.inc';
+  include_once DRUPAL_ROOT . '/core/includes/schema.inc';
   drupal_bootstrap(DRUPAL_BOOTSTRAP_DATABASE);
 
   // Check whether settings.php needs to be rewritten.