--- /usr/portage/dev-lang/lua/lua-5.1.5.ebuild	2013-03-10 17:31:09.000000000 +0100
+++ lua-5.1.5.ebuild	2013-06-04 00:14:46.000000000 +0200
@@ -76,8 +78,14 @@
 		mylibs="-lreadline"
 	fi
 
+	local myCFLAGS
+	case "${CHOST}" in
+		*-mingw*)	myCFLAGS="" ;;
+		*)			myCFLAGS="-DLUA_USE_LINUX" ;;
+	esac
+
 	cd src
-	emake CC="${CC}" CFLAGS="-DLUA_USE_LINUX ${CFLAGS}" \
+	emake CC="${CC}" CFLAGS="${CFLAGS} ${myCFLAGS}" \
 			RPATH="${EPREFIX}/usr/$(get_libdir)/" \
 			LUA_LIBS="${mylibs}" \
 			LIB_LIBS="${liblibs}" \