diff --git a/src/Jenssegers/Mongodb/Relations/EmbedsMany.php b/src/Jenssegers/Mongodb/Relations/EmbedsMany.php
index b0e40893d..96ff1eab6 100644
--- a/src/Jenssegers/Mongodb/Relations/EmbedsMany.php
+++ b/src/Jenssegers/Mongodb/Relations/EmbedsMany.php
@@ -235,8 +235,8 @@ public function attach(Model $model)
      */
     protected function associateNew($model)
     {
-        // Create a new key if needed.
-        if (!$model->getAttribute('_id')) {
+        // Create _id if needed.
+        if (!$model->getKey() && $model->getKeyName() === '_id') {
             $model->setAttribute('_id', new ObjectID);
         }