diff --git a/flake.nix b/flake.nix
index 197b6e2056ec..a6828c98fb51 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,3 +1,5 @@
+# Experimental flake interface to Nixpkgs.
+# See https://github.com/NixOS/rfcs/pull/49 for details.
 {
   edition = 201909;