diff --git a/src/messenger/webim/install/dbperform.php b/src/messenger/webim/install/dbperform.php
index 5e1abe45..9566ab39 100644
--- a/src/messenger/webim/install/dbperform.php
+++ b/src/messenger/webim/install/dbperform.php
@@ -18,6 +18,10 @@
 session_start();
 
 require_once('../libs/config.php');
+
+// Include some classes
+require_once('../libs/classes/plugin_manager.php');
+
 // Include common functions
 require_once('../libs/common/constants.php');
 require_once('../libs/common/locale.php');