diff --git a/app/views/courses/show.html.erb b/app/views/courses/show.html.erb
index 4fbf3ad43..0d48dc8d2 100644
--- a/app/views/courses/show.html.erb
+++ b/app/views/courses/show.html.erb
@@ -49,7 +49,7 @@
                   <br />
                   <%= l :label_activity_time %> ：  <%= format_activity_day(day) %>&nbsp;<%= format_time(e.event_datetime, false) %>
                 </p>
-                <%= link_to_attachments_course(e) if e.is_a?(News) %>
+                <%= link_to_attachments_course(e) if e.class.to_s == "News" %>
               </div>
               <div class="cl"></div>
             </div><!--课程动态 end-->