diff --git a/README.md b/README.md
index 66165ef..35876ea 100644
--- a/README.md
+++ b/README.md
@@ -96,3 +96,17 @@ Example usage:
       py27: commands succeeded
       congratulations :)
     $
+
+## This use of GitHub is not an endorsement
+
+This project is currently hosted by GitHub for legacy reasons.
+GitHub is not recommended as it's a service running on proprietary software
+and does not respect copyleft.
+
+[Free software needs free tools](https://mako.cc/writing/hill-free_tools.html):
+support the campaign [Give up GitHub](https://GiveUpGitHub.org) from
+[the Software Freedom Conservancy](https://sfconservancy.org).
+
+(This section is released under [CC-0](https://creativecommons.org/publicdomain/zero/1.0/).)
+
+![Logo of the GiveUpGitHub campaign](https://sfconservancy.org/img/GiveUpGitHub.png)