diff --git a/events.ics b/events.ics
index 5b38f4f1cc57d25d5a775415f1fb2bb9658337a6..b4539e8bbdab1f38f92892b52558f7c2346758f9 100644
--- a/events.ics
+++ b/events.ics
@@ -10,7 +10,8 @@ METHOD:PUBLISH
 UID:{{ event.uid }}
 ORGANIZER;CN="Chaotikum e.V.":MAILTO:{{event.contact}}
 LOCATION:Chaotikum
-SUMMARY:{{ event.short }}
+{% assign rounds = {{ event.short | size }} modulo: 70 %}
+SUMMARY:{{ rounds }}:{{ event.short }}
 CLASS:PUBLIC
 DTSTART:{{ event.eventdate | date: "%Y%m%d" }}T{{ event.eventdate | date: "%H%M%S" }}Z
 DTEND:{{ event.eventdate | date: "%Y%m%d" }}T{{ event.eventdate | date: "%H%M%S" }}Z