Installed and noticed it did not have an alt attribute. I have added some other small hacks so I am not sure if this is the right line but on about 1098 or so the code says:
$avatar = "<img src='{$src}' class='{$class} avatar-{$size} avatar-default' height='{$size}' width='{$size}' style='width: {$size}px; height: {$size}px;' />";replace with:
$avatar = "<img src='{$src}' class='{$class} avatar-{$size} avatar-default' height='{$size}' width='{$size}' style='width: {$size}px; height: {$size}px;' alt='' />";and valid!
Enjoy
