diff -r 2e52db5cdbde -r ea95004494a2 web/views/calendar.py
--- a/web/views/calendar.py	Thu Jan 20 17:14:28 2011 +0100
+++ b/web/views/calendar.py	Fri Jan 21 11:48:19 2011 +0100
@@ -31,6 +31,7 @@
 
 
 class ICalendarableAdapter(EntityAdapter):
+    __needs_bw_compat__ = True
     __regid__ = 'ICalendarable'
     __select__ = implements(ICalendarable, warn=False) # XXX for bw compat, should be abstract