diff --git a/src/applications/notification/query/PhabricatorNotificationQuery.php b/src/applications/notification/query/PhabricatorNotificationQuery.php
--- a/src/applications/notification/query/PhabricatorNotificationQuery.php
+++ b/src/applications/notification/query/PhabricatorNotificationQuery.php
@@ -181,7 +181,7 @@
 
   protected function newPagingMapFromPartialObject($object) {
     return array(
-      'key' => $object->getChronologicalKey(),
+      'key' => $object['chronologicalKey'],
     );
   }