-# You may redistribute it and/or modify it under the terms of the GNU
-# General Public License as published by the Free Software
-# Foundation; either version 2, or (at your option) any later
-# version.
+# You may redistribute this file and/or modify it under the terms of
+# the GNU General Public License as published by the Free Software
+# Foundation; either version 2, or (at your option) any later version.
+# Note however that this version of ipaddrset.py uses the Python
+# ipaddr library from Google, which is licenced only under the Apache
+# Licence, version 2.0, which is only compatible with the GNU GPL v3
+# (or perhaps later versions), and not with the GNU GPL v2.