diff --git a/plugins/kolab_addressbook/lib/kolab_addressbook_ui.php b/plugins/kolab_addressbook/lib/kolab_addressbook_ui.php
index baa63229..a1504fb8 100644
--- a/plugins/kolab_addressbook/lib/kolab_addressbook_ui.php
+++ b/plugins/kolab_addressbook/lib/kolab_addressbook_ui.php
@@ -116,7 +116,7 @@ class kolab_addressbook_ui
 
         $hidden_fields[] = array('name' => '_source', 'value' => $folder);
 
-        $folder = rcube_charse::convert($folder, RCMAIL_CHARSET, 'UTF7-IMAP');
+        $folder = rcube_charset::convert($folder, RCMAIL_CHARSET, 'UTF7-IMAP');
         $delim  = $_SESSION['imap_delimiter'];
 
         if ($this->rc->action == 'plugin.book-save') {