diff --git a/Documentation/config-hooks.txt b/Documentation/config-hooks.txt
index 95fc7bf0bb..e271ba8155 100644
--- a/Documentation/config-hooks.txt
+++ b/Documentation/config-hooks.txt
@@ -78,6 +78,15 @@ the values of hooks.patchsetCreatedHook, hooks.commentAddedHook,
 hooks.changeMergedHook and hooks.changeAbandonedHook for the
 filenames for the hooks.
 
+Missing Change URLs
+-------------------
+
+If link:config-gerrit.html#gerrit.canonicalWebUrl[gerrit.canonicalWebUrl]
+is not set in `gerrit.config` the `\--change-url` flag may not be
+passed to all hooks.  Hooks started out of an SSH context (for example
+the patchset-created hook) don't know the server's web URL, unless
+this variable is configured.
+
 See Also
 --------