moz workaround for linked images anyone?

What I'm trying to do is keep the underline on hover for text links but not on images that are in the same href as text. code is something like

a {text-decoration:none; }
a:hover {text-decoration:hover; }

text description

Mozilla (firefox) wont loose the underline under the image on hover, have tried a number of combinations, things like:

a.img:hover { }

img a:hover { }

and things like
border-style: none; text-decoration: none; background:transparent; border:0; border-bottom:0; margin:0 etc (not all together), all these work in IE and Opera but not Firefox. Even tried a class in the image.

There are several mentions around the web but no answers and no fixes that I can find

Any ideas?
Cheers