diff --git a/config/routes.rb b/config/routes.rb
index 3554da7..9409e9b 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -14,7 +14,7 @@ Rails.application.routes.draw do
               info.delete(:survey_answer_ids)
               answer_group = SurveyAnswerGroup.new(info)
             end
-            answer_group.last_modified = survey_answer.updated_at
+            answer_group.last_modified = survey_answer.created_at
             answer_group.survey_answer_ids = [survey_answer.id]
             answer_group.save
           end