diff --git a/README.md b/README.md
index 90ae8a6..0653352 100644
--- a/README.md
+++ b/README.md
@@ -71,3 +71,19 @@ When adding new code, please consider updating the Scribble
 documentation `manual.scrbl` accordingly.  I believe that good
 documentation is more important than good code, because with good docs
 you can at least know how to fix the whole thing.
+
+## License
+
+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
+[https://www.gnu.org/licenses/](https://www.gnu.org/licenses/).