diff --git a/README.md b/README.md
index 5ca51256..9616a95c 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,16 @@
-
-
-
+# Flatpak 1.2.x: end-of-life branch
+
+The Flatpak 1.2.x branch is no longer supported and does not receive
+security fixes.
+Please upgrade to a supported branch as documented in
+[SECURITY.md](https://github.com/flatpak/flatpak/blob/main/SECURITY.md).
+
+If maintainers of long-term-supported OS distributions are still
+distributing Flatpak 1.2.x, those vendors will need to either take
+responsibility for backporting security fixes, or upgrade their Flatpak
+packages.
+
+---
Flatpak is a system for building, distributing, and running sandboxed
desktop applications on Linux.