diff --git a/plugins/calendar/calendar_ui.js b/plugins/calendar/calendar_ui.js
index 47a58f82..b5425777 100644
--- a/plugins/calendar/calendar_ui.js
+++ b/plugins/calendar/calendar_ui.js
@@ -876,7 +876,7 @@ function rcube_calendar_ui(settings)
       var $dialog = $("#calendarform").dialog('close');
       
       if (!calendar)
-        calendar = { name:'', color:'cc0000' };
+        calendar = { name:'', color:'cc0000', editable:true };
       
       var form, name, color;
       
@@ -889,7 +889,7 @@ function rcube_calendar_ui(settings)
         success: function(data){
           $dialog.html(data);
           form = $('#calendarform > form');
-          name = $('#calendar-name').val(calendar.editname || calendar.name);
+          name = $('#calendar-name').prop('disabled', !calendar.editable).val(calendar.editname || calendar.name);
           color = $('#calendar-color').val(calendar.color).miniColors({ value: calendar.color });
           name.select();
         }
diff --git a/plugins/calendar/drivers/kolab/kolab_driver.php b/plugins/calendar/drivers/kolab/kolab_driver.php
index 39da2732..d01a7432 100644
--- a/plugins/calendar/drivers/kolab/kolab_driver.php
+++ b/plugins/calendar/drivers/kolab/kolab_driver.php
@@ -177,21 +177,20 @@ class kolab_driver extends calendar_driver
       $this->rc->imap_init();
       $newfolder = $this->rc->imap->mod_mailbox($newfolder, 'in');
 
-      if ($newfolder != $oldfolder)
+      if (!$cal->readonly && $newfolder != $oldfolder)
         $result = rcube_kolab::folder_rename($oldfolder, $newfolder);
       else
         $result = true;
 
       if ($result) {
         // create ID
-        $id = rcube_kolab::folder_id($newfolder);
+        $id = $newfolder ? rcube_kolab::folder_id($newfolder) : $prop['id'];
         // save color in user prefs (temp. solution)
         $prefs['kolab_calendars'] = $this->rc->config->get('kolab_calendars', array());
         unset($prefs['kolab_calendars'][$prop['id']]);
         $prefs['kolab_calendars'][$id]['color'] = $prop['color'];
 
         $this->rc->user->save_prefs($prefs);
-
         return true;
       }
     }