[plt-scheme] web-server and file names

I have two files in the web server:

shared/testfile
shared/test file

When either typing into my web browser's location box or redirecting
through redirect-to in a servlet, this works:

http://myserver/shared/testfile

while neither of these do:

http://myserver/shared/test file
http://myserver/shared/test%20file


How do I serve files with spaces in their names?

- Daniel