diff --git a/usr/local/www/system_usermanager.php b/usr/local/www/system_usermanager.php
index a736615bbd..73053ba0b9 100644
--- a/usr/local/www/system_usermanager.php
+++ b/usr/local/www/system_usermanager.php
@@ -46,6 +46,7 @@
 ##|*MATCH=system_usermanager.php*
 ##|-PRIV
 
+require_once("certs.inc");
 require("guiconfig.inc");
 
 if (isAllowedPage("system_usermanager")) {