diff --git a/plugins/calendar/drivers/kolab/kolab_calendar.php b/plugins/calendar/drivers/kolab/kolab_calendar.php
index 29bc01e5..43165421 100644
--- a/plugins/calendar/drivers/kolab/kolab_calendar.php
+++ b/plugins/calendar/drivers/kolab/kolab_calendar.php
@@ -291,7 +291,7 @@ class kolab_calendar extends kolab_storage_folder_api
         }
 
         // find and merge exception for the first instance
-        if (!empty($event['recurrence']) && is_array($event['recurrence']['EXCEPTIONS'])) {
+        if ($virtual && !empty($event['recurrence']) && is_array($event['recurrence']['EXCEPTIONS'])) {
           $event_date = $event['start']->format('Ymd');
           foreach ($event['recurrence']['EXCEPTIONS'] as $exception) {
             $exdate = $exception['recurrence_date'] ? $exception['recurrence_date']->format('Ymd') : substr($exception['_instance'], 0, 8);
diff --git a/plugins/calendar/drivers/kolab/kolab_driver.php b/plugins/calendar/drivers/kolab/kolab_driver.php
index 3e3f0fcb..0a9790c9 100644
--- a/plugins/calendar/drivers/kolab/kolab_driver.php
+++ b/plugins/calendar/drivers/kolab/kolab_driver.php
@@ -1674,10 +1674,10 @@ class kolab_driver extends calendar_driver
       unset($record['recurrence']);
 
     // add instance identifier to first occurrence (master event)
+    // do not add 'recurrence_date' though in order to keep the master even being exported as such
     if ($record['recurrence'] && !$record['recurrence_id'] && !$record['_instance']) {
-      $recurrence_id_format = $event['allday'] ? 'Ymd' : 'Ymd\THis';
-      $record['recurrence_date'] = $record['start'];
-      $record['_instance'] = $record['recurrence_date']->format($recurrence_id_format);
+      $recurrence_id_format = $record['allday'] ? 'Ymd' : 'Ymd\THis';
+      $record['_instance'] = $record['start']->format($recurrence_id_format);
     }
 
     // remove internals