is this cast valid?

[Heath Kehoe]

In current: innd/art.c, line 1211:

        if (innconf->logipaddr) {
            hops = ARTparsepath(HDR(_path), &hopcount);
-->         (const char *)av[4] = hops && hops[0] ? hops[0] : CHANname(cp);
        } else {
-->         (const char *)av[4] = Data->Feedsite;
        }

What's the deal with those casts on the lvalue?  Is that legal?  The
HP compiler says it's an error.  It will compile if I remove the casts.

-heath