diff --git a/lib/utils/to-id.js b/lib/utils/to-id.js
index <HASH>..<HASH> 100644
--- a/lib/utils/to-id.js
+++ b/lib/utils/to-id.js
@@ -10,5 +10,9 @@ module.exports = docOrIdToId
  */
 
 function docOrIdToId (docOrId) {
-  return typeof docOrId === 'object' ? docOrId._id : docOrId
+  if (typeof docOrId === 'object') {
+    return docOrId._id || docOrId.id
+  }
+
+  return docOrId
 }
fix(sync): sync objects with .id property