Weirdness with wp_mime_type_icon

Hi,

Having an odd issue with wp_mime_type_icon not returning icons for mime types that I know it should support.

For instance, if I upload a swf, view it in the library and interact with it via the media uploader interface, it is correctly represented via the interactive.png icon.

However, if I request that mime type via wp_mime_type_icon, as per below, it always defaults to default.

$img = wp_mime_type_icon('application/x-shockwave-flash');
echo $img;

I’m calling this method outside of the loop.