Globalize with uppercase locale attribute

I have this model:

class Event
    translates :nome, :descrizione
    # other stuff

Inside the database I have defined the event_translations table with
locale field as enum(‘IT’, ‘EN’)… The problem is that Globalize uses
lowercase locale, and build queries like this one:

SELECT * FROM event_translations WHERE (event_translations.locale
IN (‘it’)) AND (event_translations.event_id = 1406)

Instead of:

SELECT * FROM `event_translations` WHERE

(event_translations.locale IN (‘IT’)) AND
(event_translations.event_id = 1406)

Can you help me?
Thanks in advance