Build man pages: unkown SDATA

I've been trying to build the man pages in 8.2, unfortunately I am seeing:

$ make man
...
onsgmls  postgres.sgml | sgmlspl
/usr/share/sgml/docbook/utils-0.6.14/helpers/docbook2man-spec.pl
--lowercase --section l --date "`date '+%Y-%m-%d'`"
Unknown SDATA: [mdash ] at
/usr/share/sgml/docbook/utils-0.6.14/helpers/docbook2man-spec.pl line
1239, <STDIN> line 10730.
make: *** [man] Error 9


Doing a bit more hacking I find that the following will also cause this
error:

mdash, pi, uuml, ouml, egrave, quot, scaron, oslash


Do I need to specifically point docbook2man-spec.pl at a certain
stylesheet? Any ideas appreciated.

Cheers

Mark