diff --git a/api/src/DateTime.php b/api/src/DateTime.php
index ccf23341f8..3896997f81 100644
--- a/api/src/DateTime.php
+++ b/api/src/DateTime.php
@@ -378,15 +378,7 @@ class DateTime extends \DateTime
 			case 'integer':
 			case 'ts':
 				// EGroupware's integer timestamp is NOT the usual UTC timestamp, but has a timezone offset applied!
-				// calendar_ical unfortunately sets different timezones, breaking all sorts of things, if we're not setting the TZ back to our server-timezone
-				if (date_default_timezone_get() !== self::$server_timezone->getName())
-				{
-					$tz_backup = date_default_timezone_get();
-					date_default_timezone_set(self::$server_timezone->getName());
-				}
-				$ret = mktime(parent::format('H'),parent::format('i'),parent::format('s'),parent::format('m'),parent::format('d'),parent::format('Y'));
-				if (isset($tz_backup)) date_default_timezone_set($tz_backup);
-				return $ret;
+				return mktime(parent::format('H'),parent::format('i'),parent::format('s'),parent::format('m'),parent::format('d'),parent::format('Y'));
 			case 'utc':	// alias for "U" / timestamp in UTC
 				return $this->getTimestamp();
 			case 'object':
diff --git a/calendar/inc/class.calendar_ical.inc.php b/calendar/inc/class.calendar_ical.inc.php
index 40ef030819..0b31accff7 100644
--- a/calendar/inc/class.calendar_ical.inc.php
+++ b/calendar/inc/class.calendar_ical.inc.php
@@ -615,11 +615,11 @@ class calendar_ical extends calendar_boupdate
 								$event['end'] = new Api\DateTime($event['end'], self::$tz_cache[$event['tzid']]);
 							}
 							$event['end-nextday'] = clone $event['end'];
-							$event['end-nextday']->add("1 day");	// we need the date of the next day, as DTEND is non-inclusive (= exclusive) in rfc2445
+							$event['end-nextday']->add("60 sec");	// we need the date of the next day, as DTEND is non-inclusive (= exclusive) in rfc2445
 							foreach (array('start' => 'DTSTART','end-nextday' => 'DTEND') as $f => $t)
 							{
-								$time = new Api\DateTime($event[$f], self::$tz_cache[$event['tzid']]);
-								$arr = Api\DateTime::to($time,'array');
+								// we need to convert whole-day events to user-timezone, as only there they start at midnight
+								$arr = Api\DateTime::server2user($event[$f],'array');
 								$vevent->setAttribute($t, array('year' => $arr['year'],'month' => $arr['month'],'mday' => $arr['day']),
 									array('VALUE' => 'DATE'));
 							}