diff --git a/lib/model.js b/lib/model.js
index 3a3b3999..7d2face2 100644
--- a/lib/model.js
+++ b/lib/model.js
@@ -14,7 +14,7 @@ var List = require('./list');
 var Hookable = require('./hooks');
 var validations = require('./validations.js');
 
-var BASE_TYPES = ['String', 'Boolean', 'Number', 'Date', 'Text'];
+var BASE_TYPES = ['String', 'Boolean', 'Number', 'Date', 'Text', 'ObjectID'];
 
 /**
  * Model class: base class for all persistent objects.