diff --git a/app/helpers/watchers_helper.rb b/app/helpers/watchers_helper.rb
index 935fb440e..842e1f1b7 100644
--- a/app/helpers/watchers_helper.rb
+++ b/app/helpers/watchers_helper.rb
@@ -98,7 +98,7 @@ module WatchersHelper
     # modify by nwb
     # 主讲教师不允许退出课程
     return '' if user.id == course.tea_id
-    joined = user.member_of_course?(course)
+    joined = course.members.map{|m| m.user}.include? user
     text = joined ? l(:label_exit_course) : l(:label_new_join)
     url = joined ? join_path(:object_id => course.id) : try_join_path(:object_id => course.id)
     method = joined ? 'delete' : 'post'