diff --git a/lib/trustie/cache/clear_course_event.rb b/lib/trustie/cache/clear_course_event.rb
index 98ec8b4fd..a5f44bf45 100644
--- a/lib/trustie/cache/clear_course_event.rb
+++ b/lib/trustie/cache/clear_course_event.rb
@@ -8,9 +8,23 @@ module Trustie
           after_create :clear_course_events
         }
       end
+
       def clear_course_events
-        Rails.cache.delete("course_events_#{self.act.course_id}".to_sym) if Rails.env.production? && Setting.course_cahce_enabled?
+        if Rails.env.production? && Setting.course_cahce_enabled?
+          Rails.cache.delete(cache_key) 
+        end
+      end
+
+      def cache_key
+        course_id = nil
+        if Message === self.act
+          course_id = self.act.board.course_id
+        elsif self.act.respond_to?(:course_id)
+          course_id = self.act.course_id
+        end
+        "course_events_#{course_id}".to_sym
       end
+
     end
   end
 end