File Asociation

Hi.
First at all: Tanks for ur work and sorry by my english(i'm spanish speaker)
I use Portable Firefox in a usb pendrive and also in my desktop pc(just backup portablefirefox folder when formating... =)). I have associated *.shtml, *.htm, *.html, *.xht and *.xhtml to FirefoxPortable.exe so the asociations works fine with filenames with no spaces, but when the filename has one o more spaces firefox doesnt open the file.
Looks like FirefoxPortable.exe pass the filename to Firefox.exe without the "" ... i'm right? that can be fixed?

Thanks!!!
Grabriel.