Assuming you're doing this on a FreeBSD box, strtok(3) is obsoleted in favor of strsep(3).

And I see no point in parsing a literal, it's not going to change and you already know where the tokens are.  That is, unless this was just a quick test case and the literal will eventually be replaced with a variable.

Now I'm rambling...

If you must, -fwritable-strings to gcc.  Useful when porting non-ansi code where people assume they can write into strings.

@wxs, yeah, but I wasn't sure if strsep worked on Linux or Solaris. I can't figure out how to get libc manpages installed on ubuntu; despite 'glibc-doc' being installed, 'man strtok' doesn't show up. Sigh.

@candice, yeah, I wasn't going to go down that road. My solution was wrapping with a lame strdup()

void foo(char *x) {
  strtok(x ... )
}
...
foo(strdup("one two three"));

That'll do... 

And that road I mentioned is not for the faint of heart... it's just for a big chunk of code that expects it can do things that it can't.