diff --git a/test/unit/mailer_test.rb b/test/unit/mailer_test.rb
index 2cb5c4ca4..8d53699f3 100644
--- a/test/unit/mailer_test.rb
+++ b/test/unit/mailer_test.rb
@@ -31,7 +31,7 @@ class MailerTest < ActiveSupport::TestCase
            :wikis, :wiki_pages, :wiki_contents, :wiki_content_versions,
            :versions,
            :comments,
-           :groups_users, :watchers
+           :groups_users, :watchers, :issue_categories
 
   def setup
     ActionMailer::Base.deliveries.clear