diff --git a/phpBB/install/database_update.php b/phpBB/install/database_update.php
index 69f5f58563..211e194c73 100644
--- a/phpBB/install/database_update.php
+++ b/phpBB/install/database_update.php
@@ -60,6 +60,7 @@ if (!empty($load_extensions) && function_exists('dl'))
 }
 
 // Include files
+require($phpbb_root_path . 'includes/class_loader.' . $phpEx);
 require($phpbb_root_path . 'includes/acm/acm_' . $acm_type . '.' . $phpEx);
 require($phpbb_root_path . 'includes/cache.' . $phpEx);
 require($phpbb_root_path . 'includes/template.' . $phpEx);