Well, he got me. Perhaps I'm not most experienced, but I did a fair share of C programming back when, but not so much recently and when only ever on the same architecture (you know which). Some things I remembered (int can be 16bit), some things I was unaware of ("over shift" can be undefined? Never encountered it, but I suppose there are some broken architectures around. I know that e.g. rotate is broken on Parallax P8X32A, but you're excused for not knowing that).
Worth the (short) read, especially if you think you're an experienced C programmer ;-)