diff --git a/doc/usage.md b/doc/usage.md
index 1e4a75db47..5aeef34479 100644
--- a/doc/usage.md
+++ b/doc/usage.md
@@ -191,3 +191,5 @@ require("6to5/register")({
 6to5 also has experimental support for ES7 proposals. You can enable this with
 the `experimental: true` option when using the [Node API](#node) or
 `--experimental` when using the [CLI](#cli).
+
+**NOTE:** That these are subject to change as their proposal status progresses.