diff --git a/calendar_specification.json b/calendar_specification.json
index 5f64039..c43c5ea 100644
--- a/calendar_specification.json
+++ b/calendar_specification.json
@@ -8,7 +8,7 @@
         "http://calendars.service.z-labor.space/public.ics",
         "https://www.c3d2.de/hq.ics",
         "http://chaoschemnitz.de/chch.ical",
-        "https://open-web-calendar.herokuapp.com/calendar.ics?specification_url=https://github.com/Chaostreff-Potsdam/Chaostreff-Potsdam.github.io/blob/master/calendar-specification.json",
+        "https://open-web-calendar.herokuapp.com/calendar.ics?specification_url=https://raw.githubusercontent.com/Chaostreff-Potsdam/Chaostreff-Potsdam.github.io/master/calendar-specification.json",
         "https://calendar.google.com/calendar/ical/2eskb61g20prl65k2qd01uktis%40group.calendar.google.com/public/basic.ics",
         "http://www.netz39.de/feed/eo-events/"
     ],