diff --git a/addons/calendar/calendar.py b/addons/calendar/calendar.py
index db37a7ac505..12a1cec79f4 100644
--- a/addons/calendar/calendar.py
+++ b/addons/calendar/calendar.py
@@ -1123,7 +1123,7 @@ class calendar_event(osv.Model):
 
         def get_end_date(data):
             if data.get('end_date'):
-                data['end_date_new'] = ''.join((re.compile('\d')).findall(data.get('end_date'))) + 'T235959'
+                data['end_date_new'] = ''.join((re.compile('\d')).findall(data.get('end_date'))) + 'T235959Z'
 
             return (data.get('end_type') == 'count' and (';COUNT=' + str(data.get('count'))) or '') +\
                 ((data.get('end_date_new') and data.get('end_type') == 'end_date' and (';UNTIL=' + data.get('end_date_new'))) or '')