diff --git a/01_wait_forever/README.md b/01_wait_forever/README.md
index b1927c9b..0bd3e742 100644
--- a/01_wait_forever/README.md
+++ b/01_wait_forever/README.md
@@ -25,8 +25,8 @@
     - `#![no_std]`, `#![no_main]`
 - `cpu.S`: Assembly `_start()` function that executes `wfe` (Wait For Event), halting all cores that
   are executing `_start()`.
-- We (have to) define a `#[panic_handler]` function.
-    - Just waits infinitely for a cpu event.
+- We (have to) define a `#[panic_handler]` function to make the compiler happy.
+    - Make it `unimplemented!()` because it will be stripped out since it is not used.
 
 [inner attributes]: https://doc.rust-lang.org/reference/attributes.html