diff --git a/plugins/libkolab/lib/kolab_date_recurrence.php b/plugins/libkolab/lib/kolab_date_recurrence.php
index 5ab4532e..3197cde5 100644
--- a/plugins/libkolab/lib/kolab_date_recurrence.php
+++ b/plugins/libkolab/lib/kolab_date_recurrence.php
@@ -1,256 +1,238 @@
 <?php
 
 /**
  * Recurrence computation class for xcal-based Kolab format objects
  *
  * Utility class to compute instances of recurring events.
  * It requires the libcalendaring PHP module to be installed and loaded.
  *
  * @version @package_version@
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  *
  * Copyright (C) 2012-2016, Kolab Systems AG <contact@kolabsys.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 class kolab_date_recurrence
 {
     private /* EventCal */ $engine;
     private /* kolab_format_xcal */ $object;
     private /* DateTime */ $start;
     private /* DateTime */ $next;
     private /* cDateTime */ $cnext;
     private /* DateInterval */ $duration;
-    private /* string */ $start_time;
-    private /* string */ $end_time;
+    private /* bool */ $allday;
 
 
     /**
      * Default constructor
      *
      * @param kolab_format_xcal The Kolab object to operate on
      */
     function __construct($object)
     {
         $data = $object->to_array();
 
         $this->object = $object;
         $this->engine = $object->to_libcal();
         $this->start  = $this->next = $data['start'];
+        $this->allday = !empty($data['allday']);
         $this->cnext  = kolab_format::get_datetime($this->next);
 
-        if ($this->start && !empty($data['allday'])) {
-            $this->start_time = $data['start']->format('H:i:s');
-            if ($data['end']) {
-                $this->end_time = $data['end']->format('H:i:s');
-            }
-        }
-
         if (is_object($data['start']) && is_object($data['end'])) {
             $this->duration = $data['start']->diff($data['end']);
         }
         else {
             // Prevent from errors when end date is not set (#5307) RFC5545 3.6.1
             $seconds = !empty($data['end']) ? ($data['end'] - $data['start']) : 0;
             $this->duration = new DateInterval('PT' . $seconds . 'S');
         }
     }
 
     /**
      * Get date/time of the next occurence of this event
      *
      * @param boolean Return a Unix timestamp instead of a DateTime object
+     *
      * @return mixed  DateTime object/unix timestamp or False if recurrence ended
      */
     public function next_start($timestamp = false)
     {
         $time = false;
 
         if ($this->engine && $this->next) {
             if (($cnext = new cDateTime($this->engine->getNextOccurence($this->cnext))) && $cnext->isValid()) {
-                $next = kolab_format::php_datetime($cnext);
+                $next = kolab_format::php_datetime($cnext, $this->start->getTimezone());
                 $time = $timestamp ? $next->format('U') : $next;
 
+                if ($this->allday) {
+                    // it looks that for allday events the occurrence time
+                    // is reset to 00:00:00, this is causing various issues
+                    $next->setTime($this->start->format('G'), $this->start->format('i'), $this->start->format('s'));
+                    $next->_dateonly = true;
+                }
+
                 $this->cnext = $cnext;
                 $this->next  = $next;
             }
         }
 
         return $time;
     }
 
     /**
      * Get the next recurring instance of this event
      *
      * @return mixed Array with event properties or False if recurrence ended
      */
     public function next_instance()
     {
         if ($next_start = $this->next_start()) {
             $next_end = clone $next_start;
             $next_end->add($this->duration);
 
-            $next = $this->object->to_array();
-
-            // it looks that for allday events the occurrence time
-            // is reset to 00:00:00, this is causing various issues
-            if (!empty($next['allday'])) {
-                if ($this->start_time) {
-                    $time = explode(':', $this->start_time);
-                    $next_start->setTime((int)$time[0], (int)$time[1], (int)$time[2]);
-                }
-                if ($this->start_end) {
-                    $time = explode(':', $this->start_end);
-                    $next_end->setTime((int)$time[0], (int)$time[1], (int)$time[2]);
-                }
-            }
-
-            $next['start'] = $next_start;
-            $next['end']   = $next_end;
-
+            $next                    = $this->object->to_array();
             $recurrence_id_format    = libkolab::recurrence_id_format($next);
+            $next['start']           = $next_start;
+            $next['end']             = $next_end;
             $next['recurrence_date'] = clone $next_start;
             $next['_instance']       = $next_start->format($recurrence_id_format);
 
             unset($next['_formatobj']);
 
             return $next;
         }
 
         return false;
     }
 
     /**
      * Get the end date of the occurence of this recurrence cycle
      *
      * @return DateTime|bool End datetime of the last event or False if recurrence exceeds limit
      */
     public function end()
     {
         $event = $this->object->to_array();
 
         // recurrence end date is given
         if ($event['recurrence']['UNTIL'] instanceof DateTime) {
             return $event['recurrence']['UNTIL'];
         }
 
         // let libkolab do the work
         if ($this->engine && ($cend = $this->engine->getLastOccurrence())
             && ($end_dt = kolab_format::php_datetime(new cDateTime($cend)))
         ) {
             return $end_dt;
         }
 
         // determine a reasonable end date if none given
         if (!$event['recurrence']['COUNT'] && $event['end'] instanceof DateTime) {
             $end_dt = clone $event['end'];
             $end_dt->add(new DateInterval('P100Y'));
 
             return $end_dt;
         }
 
         return false;
     }
 
     /**
      * Find date/time of the first occurrence
      */
     public function first_occurrence()
     {
         $event      = $this->object->to_array();
         $start      = clone $this->start;
         $orig_start = clone $this->start;
         $interval   = intval($event['recurrence']['INTERVAL'] ?: 1);
 
         switch ($event['recurrence']['FREQ']) {
         case 'WEEKLY':
             if (empty($event['recurrence']['BYDAY'])) {
                 return $orig_start;
             }
 
             $start->sub(new DateInterval("P{$interval}W"));
             break;
 
         case 'MONTHLY':
             if (empty($event['recurrence']['BYDAY']) && empty($event['recurrence']['BYMONTHDAY'])) {
                 return $orig_start;
             }
 
             $start->sub(new DateInterval("P{$interval}M"));
             break;
 
         case 'YEARLY':
             if (empty($event['recurrence']['BYDAY']) && empty($event['recurrence']['BYMONTH'])) {
                 return $orig_start;
             }
 
             $start->sub(new DateInterval("P{$interval}Y"));
             break;
 
         case 'DAILY':
             if (!empty($event['recurrence']['BYMONTH'])) {
                 break;
             }
 
         default:
             return $orig_start;
         }
 
         $event['start'] = $start;
         $event['recurrence']['INTERVAL'] = $interval;
         if ($event['recurrence']['COUNT']) {
             // Increase count so we do not stop the loop to early
             $event['recurrence']['COUNT'] += 100;
         }
 
         // Create recurrence that starts in the past
         $object_type = $this->object instanceof kolab_format_task ? 'task' : 'event';
         $object      = kolab_format::factory($object_type, 3.0);
         $object->set($event);
         $recurrence = new self($object);
 
         $orig_date = $orig_start->format('Y-m-d');
         $found     = false;
 
         // find the first occurrence
         while ($next = $recurrence->next_start()) {
             $start = $next;
             if ($next->format('Y-m-d') >= $orig_date) {
-                if ($event['allday']) {
-                    $next->setTime($orig_start->format('G'), $orig_start->format('i'), $orig_start->format('s'));
-                }
-
                 $found = true;
                 break;
             }
         }
 
         if (!$found) {
             rcube::raise_error(array(
                 'file' => __FILE__,
                 'line' => __LINE__,
                 'message' => sprintf("Failed to find a first occurrence. Start: %s, Recurrence: %s",
                     $orig_start->format(DateTime::ISO8601), json_encode($event['recurrence'])),
             ), true);
 
             return null;
         }
 
-        if ($event['allday']) {
+        if ($this->allday) {
             $start->_dateonly = true;
         }
 
         return $start;
     }
 }
diff --git a/plugins/libkolab/tests/kolab_date_recurrence.php b/plugins/libkolab/tests/kolab_date_recurrence.php
index 9ea3db7b..4cd138e2 100644
--- a/plugins/libkolab/tests/kolab_date_recurrence.php
+++ b/plugins/libkolab/tests/kolab_date_recurrence.php
@@ -1,234 +1,258 @@
 <?php
 
 /**
  * kolab_date_recurrence tests
  *
  * @author Aleksander Machniak <machniak@kolabsys.com>
  *
  * Copyright (C) 2017, Kolab Systems AG <contact@kolabsys.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 class kolab_date_recurrence_test extends PHPUnit_Framework_TestCase
 {
     function setUp()
     {
         $rcube = rcmail::get_instance();
         $rcube->plugins->load_plugin('libkolab', true, true);
     }
 
     /**
      * kolab_date_recurrence::first_occurrence()
      *
      * @dataProvider data_first_occurrence
      */
     function test_first_occurrence($recurrence_data, $start, $expected)
     {
         $start = new DateTime($start);
         if (!empty($recurrence_data['UNTIL'])) {
             $recurrence_data['UNTIL'] = new DateTime($recurrence_data['UNTIL']);
         }
 
         $event  = array('start' => $start, 'recurrence' => $recurrence_data);
         $object = kolab_format::factory('event', 3.0);
         $object->set($event);
 
         $recurrence = new kolab_date_recurrence($object);
         $first      = $recurrence->first_occurrence();
 
         $this->assertEquals($expected, $first ? $first->format('Y-m-d H:i:s') : '');
     }
 
     /**
      * Data for test_first_occurrence()
      */
     function data_first_occurrence()
     {
         // TODO: BYYEARDAY, BYWEEKNO, BYSETPOS, WKST
 
         return array(
             // non-recurring
             array(
                 array(),                                     // recurrence data
                 '2017-08-31 11:00:00',                       // start date
                 '2017-08-31 11:00:00',                       // expected result
             ),
             // daily
             array(
                 array('FREQ' => 'DAILY', 'INTERVAL' => '1'), // recurrence data
                 '2017-08-31 11:00:00',                       // start date
                 '2017-08-31 11:00:00',                       // expected result
             ),
             // TODO: this one is not supported by the Calendar UI
             array(
                 array('FREQ' => 'DAILY', 'INTERVAL' => '1', 'BYMONTH' => 1),
                 '2017-08-31 11:00:00',
                 '2018-01-01 11:00:00',
             ),
             // weekly
             array(
                 array('FREQ' => 'WEEKLY', 'INTERVAL' => '1'),
                 '2017-08-31 11:00:00', // Thursday
                 '2017-08-31 11:00:00',
             ),
             array(
                 array('FREQ' => 'WEEKLY', 'INTERVAL' => '1', 'BYDAY' => 'WE'),
                 '2017-08-31 11:00:00', // Thursday
                 '2017-09-06 11:00:00',
             ),
             array(
                 array('FREQ' => 'WEEKLY', 'INTERVAL' => '1', 'BYDAY' => 'TH'),
                 '2017-08-31 11:00:00', // Thursday
                 '2017-08-31 11:00:00',
             ),
             array(
                 array('FREQ' => 'WEEKLY', 'INTERVAL' => '1', 'BYDAY' => 'FR'),
                 '2017-08-31 11:00:00', // Thursday
                 '2017-09-01 11:00:00',
             ),
             array(
                 array('FREQ' => 'WEEKLY', 'INTERVAL' => '2'),
                 '2017-08-31 11:00:00', // Thursday
                 '2017-08-31 11:00:00',
             ),
             array(
                 array('FREQ' => 'WEEKLY', 'INTERVAL' => '3', 'BYDAY' => 'WE'),
                 '2017-08-31 11:00:00', // Thursday
                 '2017-09-20 11:00:00',
             ),
             array(
                 array('FREQ' => 'WEEKLY', 'INTERVAL' => '1', 'BYDAY' => 'WE', 'COUNT' => 1),
                 '2017-08-31 11:00:00', // Thursday
                 '2017-09-06 11:00:00',
             ),
             array(
                 array('FREQ' => 'WEEKLY', 'INTERVAL' => '1', 'BYDAY' => 'WE', 'UNTIL' => '2017-09-01'),
                 '2017-08-31 11:00:00', // Thursday
                 '',
             ),
             // monthly
             array(
                 array('FREQ' => 'MONTHLY', 'INTERVAL' => '1'),
                 '2017-09-08 11:00:00',
                 '2017-09-08 11:00:00',
             ),
             array(
                 array('FREQ' => 'MONTHLY', 'INTERVAL' => '1', 'BYMONTHDAY' => '8,9'),
                 '2017-08-31 11:00:00',
                 '2017-09-08 11:00:00',
             ),
             array(
                 array('FREQ' => 'MONTHLY', 'INTERVAL' => '1', 'BYMONTHDAY' => '8,9'),
                 '2017-09-08 11:00:00',
                 '2017-09-08 11:00:00',
             ),
             array(
                 array('FREQ' => 'MONTHLY', 'INTERVAL' => '1', 'BYDAY' => '1WE'),
                 '2017-08-16 11:00:00',
                 '2017-09-06 11:00:00',
             ),
             array(
                 array('FREQ' => 'MONTHLY', 'INTERVAL' => '1', 'BYDAY' => '-1WE'),
                 '2017-08-16 11:00:00',
                 '2017-08-30 11:00:00',
             ),
             array(
                 array('FREQ' => 'MONTHLY', 'INTERVAL' => '2'),
                 '2017-09-08 11:00:00',
                 '2017-09-08 11:00:00',
             ),
             array(
                 array('FREQ' => 'MONTHLY', 'INTERVAL' => '2', 'BYMONTHDAY' => '8'),
                 '2017-08-31 11:00:00',
                 '2017-09-08 11:00:00', // ??????
             ),
             // yearly
             array(
                 array('FREQ' => 'YEARLY', 'INTERVAL' => '1'),
                 '2017-08-16 12:00:00',
                 '2017-08-16 12:00:00',
             ),
             array(
                 array('FREQ' => 'YEARLY', 'INTERVAL' => '1', 'BYMONTH' => '8'),
                 '2017-08-16 12:00:00',
                 '2017-08-16 12:00:00',
             ),
             array(
                 array('FREQ' => 'YEARLY', 'INTERVAL' => '1', 'BYDAY' => '-1MO'),
                 '2017-08-16 11:00:00',
                 '2017-12-25 11:00:00',
             ),
             array(
                 array('FREQ' => 'YEARLY', 'INTERVAL' => '1', 'BYMONTH' => '8', 'BYDAY' => '-1MO'),
                 '2017-08-16 11:00:00',
                 '2017-08-28 11:00:00',
             ),
             array(
                 array('FREQ' => 'YEARLY', 'INTERVAL' => '1', 'BYMONTH' => '1', 'BYDAY' => '1MO'),
                 '2017-08-16 11:00:00',
                 '2018-01-01 11:00:00',
             ),
             array(
                 array('FREQ' => 'YEARLY', 'INTERVAL' => '1', 'BYMONTH' => '1,9', 'BYDAY' => '1MO'),
                 '2017-08-16 11:00:00',
                 '2017-09-04 11:00:00',
             ),
             array(
                 array('FREQ' => 'YEARLY', 'INTERVAL' => '2'),
                 '2017-08-16 11:00:00',
                 '2017-08-16 11:00:00',
             ),
             array(
                 array('FREQ' => 'YEARLY', 'INTERVAL' => '2', 'BYMONTH' => '8'),
                 '2017-08-16 11:00:00',
                 '2017-08-16 11:00:00',
             ),
             array(
                 array('FREQ' => 'YEARLY', 'INTERVAL' => '2', 'BYDAY' => '-1MO'),
                 '2017-08-16 11:00:00',
                 '2017-12-25 11:00:00',
             ),
             // on dates (FIXME: do we really expect the first occurrence to be on the start date?)
             array(
                 array('RDATE' => array (new DateTime('2017-08-10 11:00:00 Europe/Warsaw'))),
                 '2017-08-01 11:00:00',
                 '2017-08-01 11:00:00',
             ),
         );
     }
 
     /**
      * kolab_date_recurrence::first_occurrence() for all-day events
      *
      * @dataProvider data_first_occurrence
      */
     function test_first_occurrence_allday($recurrence_data, $start, $expected)
     {
         $start = new DateTime($start);
         if (!empty($recurrence_data['UNTIL'])) {
             $recurrence_data['UNTIL'] = new DateTime($recurrence_data['UNTIL']);
         }
 
         $event  = array('start' => $start, 'recurrence' => $recurrence_data, 'allday' => true);
         $object = kolab_format::factory('event', 3.0);
         $object->set($event);
 
         $recurrence = new kolab_date_recurrence($object);
         $first      = $recurrence->first_occurrence();
 
         $this->assertEquals($expected, $first ? $first->format('Y-m-d H:i:s') : '');
     }
-}
 
+    /**
+     * kolab_date_recurrence::next_instance()
+     */
+    function test_next_instance()
+    {
+        date_default_timezone_set('America/New_York');
+
+        $start = new DateTime('2017-08-31 11:00:00', new DateTimeZone('Europe/Berlin'));
+        $event = array(
+            'start'      => $start,
+            'recurrence' => array('FREQ' => 'WEEKLY', 'INTERVAL' => '1'),
+            'allday'     => true,
+        );
+
+        $object = kolab_format::factory('event', 3.0);
+        $object->set($event);
+
+        $recurrence = new kolab_date_recurrence($object);
+        $next       = $recurrence->next_instance();
+
+        $this->assertEquals($start->format('2017-09-07 H:i:s'), $next['start']->format('Y-m-d H:i:s'), 'Same time');
+        $this->assertEquals($start->getTimezone()->getName(), $next['start']->getTimezone()->getName(), 'Same timezone');
+        $this->assertSame($next['start']->_dateonly, true, '_dateonly flag');
+    }
+}