diff --git a/lib/common.php b/lib/common.php
index 5e8eae6e72..03b8bd52a5 100644
--- a/lib/common.php
+++ b/lib/common.php
@@ -101,6 +101,8 @@ $config['db'] =
 
 require_once(INSTALLDIR.'/config.php');
 
+require_once('Validate.php');
+
 if (function_exists('date_default_timezone_set')) {
 	/* Work internally in UTC */
 	date_default_timezone_set('UTC');