closing string output ports?

[Nic]

Using 1.6.4 I've been implementing a soft port that simply wraps a
closured port adding chunked transport encoding (an HTTP feature) to
the stream.

I presumed that my close-port proc would have to call close-port on
the real port. But when I test that with a string port I get a
segementation fault:


(call-with-output-string
   (lambda (prt)
     (display "pah!" prt)
     (close-port prt)))

Should my soft port close-port impl call close-port on the underlying
port?

Is there a bug in guile 1.6.4?

If that's not right: what should I do instead?


-- 
Nic Ferrier
http://www.tapsellferrier.co.uk