diff --git a/app/controllers/bids_controller.rb b/app/controllers/bids_controller.rb
index f61ed35f6..499d90a92 100644
--- a/app/controllers/bids_controller.rb
+++ b/app/controllers/bids_controller.rb
@@ -373,7 +373,7 @@ class BidsController < ApplicationController
   #by xianbo
   def homework_destroy
     @bid_to_destroy = Bid.find params[:course_id]
-    (render_403; return false) unless User.current.admin?||User.current.id==bid.author_id
+    (render_403; return false) unless User.current.admin?||User.current.id==@bid_to_destroy.author_id
     @bid_to_destroy.destroy
     respond_to do |format|
       format.html { redirect_to :back }