Have you looked at http://www.math.utah.edu/~beebe/software/ieee/ ? Which says:
"All C programs can also be compiled with old-style Kernighan and
Ritchie C. However, inasmuch as I now have access to only one such
old compiler, with more than 35 others supporting 1989 Standard C,
I no longer attempt to retain K&R compatibility in new code.
If you run into trouble, perhaps Nelson has older versions stashed away?
