Hello, Zack, I don't know the answer, but I have a hunch that may hopefully ring a bell for someone who went through those pains: the included headers relied heavily on ioctl macros, that, on early Unices, often abused pre-std preprocessor macro quirks about quoting, in ways that would only have the intended effect with -traditional preprocessing. We have (had?) fixinclude code for such pre-std ioctls in GCC. I hope this helps, -- Alexandre Oliva, happy hacker https://FSFLA.org/blogs/lxo/ Free Software Activist GNU Toolchain Engineer Disinformation flourishes because many people care deeply about injustice but very few check the facts. Ask me about <https://stallmansupport.org>