diff --git a/app/models/issue.rb b/app/models/issue.rb
index a89f23dd8..0c691f355 100644
--- a/app/models/issue.rb
+++ b/app/models/issue.rb
@@ -1390,6 +1390,7 @@ class Issue < ActiveRecord::Base
     s << ' child' if child?
     s << ' parent' unless leaf?
     s << ' private' if is_private?
+    s << ' behind-schedule' if behind_schedule?
     if user.logged?
       s << ' created-by-me' if author_id == user.id
       s << ' assigned-to-me' if assigned_to_id == user.id
diff --git a/test/unit/issue_test.rb b/test/unit/issue_test.rb
index d82f6e079..940825a4a 100644
--- a/test/unit/issue_test.rb
+++ b/test/unit/issue_test.rb
@@ -3021,6 +3021,11 @@ class IssueTest < ActiveSupport::TestCase
     assert_include 'assigned-to-me', issue2.css_classes(user)
   end
 
+  def test_css_classes_behind_schedule
+    assert_include 'behind-schedule', Issue.find(1).css_classes.split(' ')
+    assert_not_include 'behind-schedule', Issue.find(2).css_classes.split(' ')
+  end
+
   def test_save_attachments_with_hash_should_save_attachments_in_keys_order
     set_tmp_attachments_directory
     issue = Issue.generate!