diff --git a/src/workflow/diff/ArcanistDiffWorkflow.php b/src/workflow/diff/ArcanistDiffWorkflow.php
index 283bdab7..840c3008 100644
--- a/src/workflow/diff/ArcanistDiffWorkflow.php
+++ b/src/workflow/diff/ArcanistDiffWorkflow.php
@@ -1524,6 +1524,7 @@ EOTEXT
       rtrim($comments).
       "\n\n".
       "# Enter a brief description of the changes included in this update.\n".
+      "# The first line is used as subject, next lines as comment.\n".
       "#\n".
       "# If you intended to create a new revision, use:\n".
       "#  $ arc diff --create\n".