diff --git a/src/applications/differential/controller/DifferentialChangesetViewController.php b/src/applications/differential/controller/DifferentialChangesetViewController.php
index fc0536902c..0c02da5b55 100644
--- a/src/applications/differential/controller/DifferentialChangesetViewController.php
+++ b/src/applications/differential/controller/DifferentialChangesetViewController.php
@@ -175,6 +175,7 @@ final class DifferentialChangesetViewController extends DifferentialController {
 
     $can_mark = false;
     $object_owner_phid = null;
+    $revision = null;
     if ($revision_id) {
       $revision = id(new DifferentialRevisionQuery())
         ->setViewer($viewer)