Risky...just pop it down bike garage for 2 secs to make sure...if they are nice they wont even charge for it
Failing that can get the correct tool on ebay for a cpl of quid.
Actually come to think of it if your in the Trowbridge area look up GM Stevenson...
http://www.nutz4bikes.co.uk/
Not used them myself but meant to be good, I'm sure they can help you out