I cannot validate my site with W3C

My site http://nokiawindowsphone.pl does not validate on W3C Markup Validation Service (validator.w3.org) - i receive message:

Sorry, I am unable to validate this document because on line 195 it contained one or more bytes that I cannot interpret as utf-8 (in other words, the bytes found are not valid values in the specified Character Encoding). Please check both the content of the file and the character encoding indication.

The error was: utf8 "\xB9" does not map to Unicode

/* Lumia - prostok�t 300 */

This is the problem. Change "ą" to "a" and everything should work great.