diff --git a/birthdays-cal.py b/birthdays-cal.py
index 5155453..24f6dd5 100644
--- a/birthdays-cal.py
+++ b/birthdays-cal.py
@@ -8,8 +8,6 @@ from bisect import bisect
 import yaml
 from icalendar import Calendar, Event
 
-one_day = datetime.date(1, 1, 2) - datetime.date(1, 1, 1)
-
 event_config = {'description': '', 'categories': '', 'language': ''}
 
 zsigns = [(1, 20, '♑'), (2, 18, '♒'), (3, 20, '♓'),  (4, 20, '♈'),
@@ -85,7 +83,7 @@ def make_event(person, year):
     event.add('dtstamp',     datetime.datetime(
         event_date.year, event_date.month, event_date.day))
     event.add('dtstart',     event_date)
-    event.add('duration',    one_day)
+    event.add('dtend',       event_date)
     event.add('created',     datetime.datetime.utcnow())
     event.add('last-modified', datetime.datetime.utcnow())
     return event