diff --git a/app/controllers/homework_common_controller.rb b/app/controllers/homework_common_controller.rb
index 1b556c3c6..0f4ddf8d8 100644
--- a/app/controllers/homework_common_controller.rb
+++ b/app/controllers/homework_common_controller.rb
@@ -426,7 +426,7 @@ class HomeworkCommonController < ApplicationController
                   changesets = g.commits(project.gpid, :ref_name => default_branch)
                   changesets_latest_coimmit = changesets[0]
                   unless changesets[0].blank?
-                    if time < changesets_latest_coimmit.created_at
+                    if format_time(time) < format_time(changesets_latest_coimmit.created_at)
                       time = changesets_latest_coimmit.created_at
                     end
                   end