diff --git a/src/applications/differential/view/addcomment/DifferentialAddCommentView.php b/src/applications/differential/view/addcomment/DifferentialAddCommentView.php
index b3305debe4..78d845a680 100644
--- a/src/applications/differential/view/addcomment/DifferentialAddCommentView.php
+++ b/src/applications/differential/view/addcomment/DifferentialAddCommentView.php
@@ -104,7 +104,15 @@ final class DifferentialAddCommentView extends AphrontView {
           ->setID('comment-content')
           ->setLabel('Comment')
           ->setEnableDragAndDropFileUploads(true)
-          ->setValue($this->draft))
+          ->setValue($this->draft)
+          ->setCaption(phutil_render_tag(
+            'a',
+            array(
+              'href' => PhabricatorEnv::getDoclink(
+                'article/Remarkup_Reference.html'),
+              'target' => '_blank',
+            ),
+            'Remarkup Reference')))
       ->appendChild(
         id(new AphrontFormSubmitControl())
           ->setValue($is_serious ? 'Submit' : 'Clowncopterize'));
diff --git a/src/applications/differential/view/addcomment/__init__.php b/src/applications/differential/view/addcomment/__init__.php
index 352c41acd1..fed62292bc 100644
--- a/src/applications/differential/view/addcomment/__init__.php
+++ b/src/applications/differential/view/addcomment/__init__.php
@@ -20,6 +20,7 @@ phutil_require_module('phabricator', 'view/form/control/tokenizer');
 phutil_require_module('phabricator', 'view/form/error');
 phutil_require_module('phabricator', 'view/layout/panel');
 
+phutil_require_module('phutil', 'markup');
 phutil_require_module('phutil', 'utils');