diff --git a/src/applications/markup/engine/PhabricatorMarkupEngine.php b/src/applications/markup/engine/PhabricatorMarkupEngine.php
index 3f1a9f1f13..071002ed9b 100644
--- a/src/applications/markup/engine/PhabricatorMarkupEngine.php
+++ b/src/applications/markup/engine/PhabricatorMarkupEngine.php
@@ -78,6 +78,7 @@ class PhabricatorMarkupEngine {
       'custom-inline' => array(),
       'custom-block'  => array(),
       'differential.diff' => null,
+      'header.generate-toc' => false,
       'macros'        => true,
       'uri.allowed-protocols' => PhabricatorEnv::getEnvConfig(
         'uri.allowed-protocols'),