CSS Hacks Breaking Validation

I had nice valid CSS, then I bumped into IE 5.5. So I added a few hacks to make it look right in IE 5.5 and it broke the validation. I am not amused.

Seems the validator doesn’t like the ‘/’ hacks.

* html #sidebar ul li { /* feed IE only */
  /text-indent: -15px; /* for IE 5.0 and IE 5.5 */
  text-indent: /**/0; /* reset all except IE 5.5 */
  t/ext-indent: 0;

How do I work around this? Or do I just have to live with invalid CSS if I want it to look right?