diff --git a/flaskext/mongoalchemy.py b/flaskext/mongoalchemy.py
index <HASH>..<HASH> 100644
--- a/flaskext/mongoalchemy.py
+++ b/flaskext/mongoalchemy.py
@@ -122,7 +122,7 @@ class Document(document.Document):
     def get(cls, mongo_id):
         """Returns a document instance from its mongo_id"""
         query = cls._session.query(cls)
-        return query.filter(cls.f.mongo_id==mongo_id).first()
+        return query.filter(cls.mongo_id==mongo_id).first()
 
     def __cmp__(self, other):
         if isinstance(other, type(self)) and self.has_id() and other.has_id():
Updated query API for new MongoAlchemy version (<I>)