diff --git a/app/controllers/exercise_controller.rb b/app/controllers/exercise_controller.rb
index 2c1ad31c1..d1df22dff 100644
--- a/app/controllers/exercise_controller.rb
+++ b/app/controllers/exercise_controller.rb
@@ -5,8 +5,11 @@ class ExerciseController < ApplicationController
   before_filter :find_course, :only => [:index,:new,:create,:student_exercise_list]
   include ExerciseHelper
 
-  include ExerciseHelper
   def index
+    if @course.is_public == 0 && !User.current.member_of_course?(@course)
+      render_403
+      return
+    end
     remove_invalid_exercise(@course)
     @is_teacher = User.current.allowed_to?(:as_teacher,@course)
     if @is_teacher