Headstock cracking - how to salvage?

[carboxymoron]

I was cleaning up an old classical guitar that's been unused for years and noticed that there's a crack developing at the headstock. The weak point is where one of the tuning heads is screwed into the wood and the crack is quite bad across -- looks like one good knock will break off a whole chunk of wood. Is there anything that can be done to save it now, or can it only be glued back after it actually breaks?

I don't particularly care about it looking nice and I'm not inclined to spend much money on it either. So any kind of DIY solution will be welcome. Will post pics later.

 

[CyanideJunkie]

Loosen the screw slightly first before attempting anything else.