[plt-scheme] web-server and IPv6?

I can't seem to get the web-server to run using the SVN trunk code:

dro:/home/web# web-server-text
tcp-listen: listen on 80 failed (Address family not supported by protocol; errno=97)

It works if I supply the -a argument (using my local IP address,
namely 192.168.1.21), but now the log file says that every request
comes from 192.168.1.21, e.g. 

  (from "192.168.1.21" to "192.168.1.21" for "/" at "Monday, November 7th, 2005 4:26:36pm")

And anyway, I'd rather not have to specify the IP address, in case I
decide to rearrange my local net.  Is there a way to get this to work?
(I'm running Debian Linux 2.4.21-1-k7; I haven't done anything special
to enable IPv6, but I wouldn't be surprised if it's on by default.)

--dougo at place.org