diff --git a/lib/tasks/homework_evaluation.rake b/lib/tasks/homework_evaluation.rake
index d1fad8f14..56c46179c 100644
--- a/lib/tasks/homework_evaluation.rake
+++ b/lib/tasks/homework_evaluation.rake
@@ -24,7 +24,7 @@ namespace :homework_evaluation do
             student_works = homework_common.student_works.has_committed
           end
 
-          if student_works.size >= 2
+          if student_works.present? && student_works.length >= 2
             HomeworkEvaluationCommentAssginJob.perform_later(homework_common.id)
 
             homework_detail_manual.update_column('comment_status', 3)