Not so much bungled as got bitten by a change in behavior. Amusingly, “Return Values” still states the old behavior, to which standard the program is correct.

I'll fix the program.

By the way, the zip archives include a Makefile with correct compiler configuration (namely -std=c99). I tried downloading them after seeing this thread and it didn't work; I've re-uploaded them and now they download correctly, Makefiles and all. No more having to run the compiler by hand.