diff --git a/app/controllers/student_work_controller.rb b/app/controllers/student_work_controller.rb
index 593d6bf53..018a293e3 100644
--- a/app/controllers/student_work_controller.rb
+++ b/app/controllers/student_work_controller.rb
@@ -631,7 +631,7 @@ class StudentWorkController < ApplicationController
       unless @homework.save
         logger.debug @homework.errors.full_messages
       else
-        student_work = @homework.student_works.where(user_id: User.current.id).first
+        student_work = StudentWork.where(homework_common_id: @homework.id, user_id: User.current.id).first
       end
     end
     student_work
diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
index 9b2d49f2d..d71b24fc8 100644
--- a/app/controllers/users_controller.rb
+++ b/app/controllers/users_controller.rb
@@ -354,7 +354,7 @@ class UsersController < ApplicationController
       @user = User.current
       @homework = HomeworkCommon.find(params[:homework_id])
       @is_test = params[:is_test] == 'true'
-      @student_work = @homework.student_works.where(user_id: User.current.id).first
+      @student_work = StudentWork.where(homework_common_id: @homework.id, user_id: User.current.id).first
       if @student_work.nil?
         @student_work = StudentWork.new
       end
@@ -369,7 +369,7 @@ class UsersController < ApplicationController
 
   def user_commit_homework
     homework = HomeworkCommon.find(params[:homework])
-    student_work = homework.student_works.where(user_id: User.current.id).first
+    student_work = StudentWork.where(homework_common_id: homework.id, user_id: User.current.id).first
     if student_work
       student_work.save
       flash[:notice] = l(:notice_successful_create)