diff --git a/rust/config/allowed_list.go b/rust/config/allowed_list.go
index 62d469e..483dddb 100644
--- a/rust/config/allowed_list.go
+++ b/rust/config/allowed_list.go
@@ -1,6 +1,10 @@
 package config
 
 var (
+	// When adding a new path below, add a rustfmt.toml file at the root of
+	// the repository and enable the rustfmt repo hook. See aosp/1347562
+	// for an example.
+	// TODO(b/160223496): enable rustfmt globally.
 	RustAllowedPaths = []string{
 		"external/minijail",
 		"external/rust",