diff --git a/features-tree.scm b/features-tree.scm
index d4fc8c5..24d7069 100644
--- a/features-tree.scm
+++ b/features-tree.scm
@@ -1,3 +1,21 @@
+#|
+Features Tree, creates graphviz-compatible files from Scheme trees.
+Copyright (C) 2019 Lucien "Phundrak" Cartier-Tilet
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+|#
+
 (define (declare-node node-text node-generation)
   (string-append (number->string node-generation)
                  "[label=\""