diff --git a/plugins/calendar/drivers/kolab/kolab_driver.php b/plugins/calendar/drivers/kolab/kolab_driver.php
index 09117f5d..e54e083f 100644
--- a/plugins/calendar/drivers/kolab/kolab_driver.php
+++ b/plugins/calendar/drivers/kolab/kolab_driver.php
@@ -803,7 +803,6 @@ class kolab_driver extends calendar_driver
    */
   public function get_freebusy_list($email, $start, $end)
   {
-    require_once('Horde/iCalendar.php');
     require_once('HTTP/Request2.php');
 
     if (empty($email)/* || $end < time()*/)
@@ -865,7 +864,7 @@ class kolab_driver extends calendar_driver
 
     // parse free-busy information using Horde classes
     if ($fbdata) {
-      $fbcal = new Horde_iCalendar;
+      $fbcal = $this->cal->get_ical()->get_parser();
       $fbcal->parsevCalendar($fbdata);
       if ($fb = $fbcal->findComponent('vfreebusy')) {
         $result = array();
diff --git a/plugins/calendar/lib/calendar_ical.php b/plugins/calendar/lib/calendar_ical.php
index 5aa51953..db803efe 100644
--- a/plugins/calendar/lib/calendar_ical.php
+++ b/plugins/calendar/lib/calendar_ical.php
@@ -121,7 +121,7 @@ class calendar_ical
   /**
    * Load iCal parser from the Horde lib
    */
-  private function get_parser()
+  public function get_parser()
   {
     // use Horde:iCalendar to parse vcalendar file format
     @include_once('Horde/iCalendar.php');