diff --git a/js/server/modules/org/arangodb/simple-query.js b/js/server/modules/org/arangodb/simple-query.js
index 34e30e3918..07a1588e5d 100644
--- a/js/server/modules/org/arangodb/simple-query.js
+++ b/js/server/modules/org/arangodb/simple-query.js
@@ -112,7 +112,7 @@ function byExample (collection, example, skip, limit) {
       if (example[k] === null) {
         unique = false;
       }
-      else if (k === '_id') {
+      else if (k === '_id' || k === '_key') {
         // example contains the document id in attribute "_id"
         documentId = example[k];
         break;