FF underlines anchor images

[liunx]

When placing an image inside an <a> tag, how do I remove the underline from the image, but not the anchor text?
This code works in NS and IE but FF underlines the image...

<a href=http://www.webdeveloper.com/forum/archive/index.php/"mypage.html">
<img src=http://www.webdeveloper.com/forum/archive/index.php/"myimage.jpg" width="100" height="100" alt="myimage"><br>
My Link</a></td>

img {border:0; text-decoration:none;}
doesn't seem to work.a {text-decoration:none;}
a span{text-decoration:underline;}

<a href=http://www.webdeveloper.com/forum/archive/index.php/"mypage.html">
<img src=http://www.webdeveloper.com/forum/archive/index.php/"myimage.jpg" width="100" height="100" alt="myimage"><br>
<span>My Link</span></a></body>