I get the error: Undefined index: myId in /Jenssegers/Mongodb/Query/Builder.php:575 It looks like the Builder class is hard-coded to expect the key as _id: `return $sequence == '_id' ? $result->getInsertedId() : $values[$sequence];` This causes problems when doing a find($id) when you've modified the primaryKey to be something else in the model class. `public $primaryKey = 'myId';` I'm using the latest master version using PHP7 and Mongo 3.4