Is "caught you unawares" correct?

I read a book and came across "caught you unawares". I kept thinking it's supposed to be "caught you unaware".

Is this an acceptable form or was that a typo or something?

This is a correct form. Unawares is an adverb meaning "while not aware of something" or "by surprise". Caught needs an adverb complement, so unawares fits nicely. It turns out unawares was actually Random House's word of the day several years back, and this does a nice job of explaining it.

It's the correct form, "unawares"is the adverb form of the adjective "unaware" and caught calls for an adverb complement rather than an adjective.

Sorry, couldn't resist:

Bananas in pyjamas
Are coming down the stairs
Bananas in pyjamas
Are coming down in pairs
Bananas in pyjamas
Are chasing teddy bears
'Cause on Tuesdays
They all try to
Catch them unawares