diff --git a/dav_events/templatetags/dav_events.py b/dav_events/templatetags/dav_events.py
index 4449da5..cbeac1d 100644
--- a/dav_events/templatetags/dav_events.py
+++ b/dav_events/templatetags/dav_events.py
@@ -96,13 +96,13 @@ def render_event_changelog(event):
                 icon = u'flag'
                 status = get_or_create_event_status(change.content)
                 content_html = format_html(raise_flag_templ,
-                                           bcontext=status.bootstrap_context,
+                                           bcontext=status.bootstrap_context or u'default',
                                            label=status.label)
             elif change.operation == EventChange.LOWER_FLAG:
                 icon = u'flag'
                 status = get_or_create_event_status(change.content)
                 content_html = format_html(lower_flag_templ,
-                                           bcontext=status.bootstrap_context,
+                                           bcontext=status.bootstrap_context or u'default',
                                            label=status.label)
             else:
                 icon = u'question-sign'