diff --git a/helpers/make-cpio-doc b/helpers/make-cpio-doc
index 8958180..5186d4f 100644
--- a/helpers/make-cpio-doc
+++ b/helpers/make-cpio-doc
@@ -16,6 +16,9 @@
 #    along with this program. If not, see <http://www.gnu.org/licenses/>.
 
 VERSION=1
+
+# cpio-doc is under GFDL but due to "invariant sections" is considered
+# problematic for Debian
 EXTERNAL='deb-src http://archive.ubuntu.com/ubuntu main multiverse
 
 . ./config