diff --git a/calendar/inc/class.calendar_bo.inc.php b/calendar/inc/class.calendar_bo.inc.php
index 44ec0f9883..f0a7f246bb 100644
--- a/calendar/inc/class.calendar_bo.inc.php
+++ b/calendar/inc/class.calendar_bo.inc.php
@@ -773,7 +773,7 @@ class calendar_bo
 		foreach ($events as &$event)
 		{
 			// convert timezone id of event to tzid (iCal id like 'Europe/Berlin')
-			if (!$event['tz_id'] || !($event['tzid'] = calendar_timezones::id2tz($event['tz_id'])))
+			if (empty($event['tzid']) && (!$event['tz_id'] || !($event['tzid'] = calendar_timezones::id2tz($event['tz_id']))))
 			{
 				$event['tzid'] = egw_time::$server_timezone->getName();
 			}
diff --git a/calendar/inc/class.calendar_uiforms.inc.php b/calendar/inc/class.calendar_uiforms.inc.php
index 66bb4bb2a0..52498a9c6d 100644
--- a/calendar/inc/class.calendar_uiforms.inc.php
+++ b/calendar/inc/class.calendar_uiforms.inc.php
@@ -1135,6 +1135,9 @@ class calendar_uiforms extends calendar_ui
 				}
 				else
 				{
+					// as icaltoegw returns timestamps in server-time, we have to convert them here to user-time
+					$this->bo->db2data($events, 'ts');
+
 					$event = array_shift($events);
 					if (($existing_event = $this->bo->read($event['uid'])))
 					{