That's the function definition, not its declaration. It's pre-ANSI C, so that semicolon can mislead. I didn't bother to grab the source to check whatever the header said (or, heh, didn't say, per OpenBSD convention), but I'm going to assume it was correct.

It amuses me greatly that we're sitting here arguing over the minutiae of coding standards when this thing is still written in K&R syntax.

But regardless: whatever the header said, it wouldn't have affected this bug, which was just a straightforward transpose thing between compatible types. People get memcpy() reversed all the time too, and frankly I don't know if I've ever looked at its function declaration in a header.