diff --git a/settings/templatetags/template_filters.py b/settings/templatetags/template_filters.py
index a0e67d61..bd18780d 100644
--- a/settings/templatetags/template_filters.py
+++ b/settings/templatetags/template_filters.py
@@ -115,9 +115,12 @@ def add_month(date, month=1):
 
 @register.filter
 def in_calendar(event, user):
-    if event:
-        calendar = user.calendar
-        return calendar.check_in_calendar(event)
+    if user.is_authenticated():
+        if event:
+            calendar = user.calendar
+            return calendar.check_in_calendar(event)
+        else:
+            return False
     else:
         return False
     """