Updating NHibernate version

I'm updating NHibernate version of a project and comes across a few errors.

NHibernate.ISession' does not contain a definition for 'Linq'

It seems session.Linq<T>() is gone. An answer on StackOverflow says I need to use session.Query<T>() instead.

session.Linq<T>() is for the contrib provider for NHibernate 2.x
session.Query<T>() is for the built-in provider in NHibernate 3.x