FD_SET Problem

[Andrew Wiley]

I'm on 64 bit linux (though with a self-built 32 bit DMD), and this testcase
is failing for me:
import std.stdio;
import core.sys.posix.sys.select;

int main(string[] args) {
   fd_set fdset;
   FD_SET(3, &fdset);
   assert(FD_ISSET(3, &fdset));
   return 0;
}

The same program works perfectly with GDC. Is this a DMD bug, or am I just
missing something?