Default Date Format in Rails (Need it to be ddmmyyyy)

I've been working with a rails form all day and I was just randomly testing it and tried the date 25/12/2009 and it came up with a huge error.

It was at this point I realised that rails is set to american date mode (mm/dd/yyyy) instead of the UK style: dd/mm/yyyy.

How can I set rails to automatically deal with all dates in dd/mm/yyyy format?