diff --git a/agenda/calendar.py b/agenda/calendar.py
index 56ef6c8..039c546 100644
--- a/agenda/calendar.py
+++ b/agenda/calendar.py
@@ -61,7 +61,7 @@ def build_events(events: list[Event]) -> list[dict[str, typing.Any]]:
             continue
 
         if e.has_time:
-            end = e.end_date or e.date + timedelta(hours=1)
+            end = e.end_date or e.date + timedelta(minutes=30)
         else:
             end = (e.end_as_date if e.end_date else e.as_date) + one_day
         item = {