Favicon.ico

Hi, I learned that IE only supports favicon.ico (see: http://en.wikipedia.org/wiki/Favicon) Yet, in Theme Options, if I select the favicon on my computer (an *.ico file, pictogram) for upload, the file is renamed to *.png ?? Hence, the favicon is not visible in IE, where is does in Chrome for example. Any idea?? You can download this favicon here: http://db.tt/iMUiYjhW