ASP.NET MVC 2 wildcard route has trouble handling spaces

Question

I've got a wildcard route mapped as below:

        routes.MapRoute(
            null,
            "{controller}/{action}/{*category}",
            new { controller = "Mall", action = "Index", category = UrlParameter.Optional }
        );

This has been working fine until the category has any spaces before or after slashes " / ".

For the category ART/MUSIC, it will find the page fine.

For the category ART / MUSIC, it will give me a 404 not found.

Any help would be much appreciated!