GCC 3.3.2: Some bug in the preprocessor?

Look, this defun returns 0, and this is correct:

tst()
{
#if (unsigned)0 > -1
    return 1;
#else
    return 0;
#endif
}

But this one returns 1, and this is incorrect:

tst()
{
#if 0 > (unsigned)-1
    return 1;
#else
    return 0;
#endif
}

What's wrong?