error: reference to 'group' is ambiguous

I'm getting this error wrapping a C++ library:

Group.c: In function 'void XS_Foo__Group_new(PerlInterpreter*, CV*)':
Group.c:84: error: reference to 'group' is ambiguous
/usr/include/grp.h:44: error: candidates are: struct group
group.h:41: error:                 class foo::group

/usr/include/grp.h is pulled in perl.h, so obviously compiling with
-nostdlib is no possible.

If I try to make the type unambiguous by specifying foo::group in the
.xs, then I get typemap problems, which get worse if I include foo::
in group in the typemap as well.

Any suggestions?

Thanks for any help.

Regards

Jeff