diff --git a/plugins/calendar/calendar_ui.js b/plugins/calendar/calendar_ui.js
index b24df470..1e83bbd0 100644
--- a/plugins/calendar/calendar_ui.js
+++ b/plugins/calendar/calendar_ui.js
@@ -2320,7 +2320,6 @@ function rcube_calendar_ui(settings)
             delete data.rsvp;  // unset RSVP flag
           }
         }
-        event_show_dialog(me.selected_event);
 
         // submit status change to server
         var submit_data = $.extend({}, me.selected_event, { source:null, comment:$('#reply-comment-event-rsvp').val() }),
@@ -2333,6 +2332,8 @@ function rcube_calendar_ui(settings)
           me.saving_lock = rcmail.set_busy(true, 'calendar.savingdata');
           rcmail.http_post('event', { action:'rsvp', e:submit_data, status:response, noreply:noreply });
         }
+
+        event_show_dialog(me.selected_event);
       }
     };
     
diff --git a/plugins/calendar/drivers/kolab/kolab_calendar.php b/plugins/calendar/drivers/kolab/kolab_calendar.php
index 0ea41e60..e5126e9c 100644
--- a/plugins/calendar/drivers/kolab/kolab_calendar.php
+++ b/plugins/calendar/drivers/kolab/kolab_calendar.php
@@ -650,6 +650,11 @@ class kolab_calendar extends kolab_storage_folder_api
       $event['recurrence'] = array();
     }
 
+    // keep 'comment' from initial itip invitation
+    if (!empty($old['comment'])) {
+      $event['comment'] = $old['comment'];
+    }
+
     // remove some internal properties which should not be saved
     unset($event['_savemode'], $event['_fromcalendar'], $event['_identity'], $event['_folder_id'], $event['className']);