image preview impossible if image name contains special characters

We uploaded an image called pm²logo.gif to one of our wiki pages. Clicking on the image link for the attachment page gave a correct image. Embedding this image on a wiki page was also ok : [pm²logo.gif].

Visualing this image with the image preview on the attachment page (by clicking on the >> sign) resulted in an image not being shown.

If we changed the "²" in the filename to another character, eg "2", the image preview behaves correctly. This lead us in supposing that the image preview could have a problem with special characters in the file name.