--- groff-1.20.1-r1.ebuild	2009-03-11 17:59:14.566850657 +0000
+++ groff-1.20.1-r1.ebuild	2009-03-11 17:53:29.217159703 +0000
@@ -42,6 +42,17 @@
 			doc/Makefile.sub || die "cross-compile sed failed"
 	fi
 
+	# Brand mandoc generated man pages as Gentoo
+	local OS="Linux"
+	if use kernel_FreeBSD; then
+		OS="FreeBSD"
+	elif use userland_BSD; then
+		OS="BSD"
+	fi
+	echo ".ds volume-operating-system Gentoo" >> tmac/mdoc.local
+	echo ".ds operating-system Gentoo ${OS}" >> tmac/mdoc.local
+	echo ".ds default-operating-system Gentoo ${OS}" >> tmac/mdoc.local
+
 	if use linguas_ja ; then
 		epatch "${WORKDIR}"/${P}-japanese.patch #255292
 		eautoconf