Objective C: Atomic decrement of integer without @synchronized?

If I use

@property (atomic,assign) int value;

and later access it like so

self.value--;

is that decrement atomic? Because if I had to do this:

self.value = self.value - 1;

then I am sure there would be a chance of a race condition between the read and the write.

My instinct of course is to just do this

@synchronized(self) { value--; }

but I am being told that is not kosher.

Thanks.