diff --git a/data/theme/gnome-shell-sass/README.md b/data/theme/gnome-shell-sass/README.md
index 7d6090ffe..a5f219aed 100644
--- a/data/theme/gnome-shell-sass/README.md
+++ b/data/theme/gnome-shell-sass/README.md
@@ -3,8 +3,14 @@ GNOME Shell Sass is a project intended to allow the sharing of the
 theme sources in sass between gnome-shell and other projects like
 gnome-shell-extensions.
 
+Any changes should be done in the [GNOME Shell subtree][shell-subtree]
+and not the stand-alone [gnome-shell-sass repository][sass-repo]. They
+will then be synchronized periodically before releases.
+
 ## License
 GNOME Shell Sass is distributed under the terms of the GNU General Public
 License, version 2 or later. See the [COPYING][license] file for details.
 
+[shell-subtree]: https://gitlab.gnome.org/GNOME/gnome-shell/tree/master/data/theme/gnome-shell-sass
+[sass-repo]: https://gitlab.gnome.org/GNOME/gnome-shell-sass
 [license]: COPYING