1 files changed, 5 insertions, 3 deletions
diff --git a/src/examples/_3_preemption.rs b/src/examples/_3_preemption.rs
index 1f6b244b..9dc8983b 100644
--- a/src/examples/_3_preemption.rs
+++ b/src/examples/_3_preemption.rs
@@ -2,7 +2,6 @@
 //!
 //! ```
 //! #![deny(unsafe_code)]
-//! #![feature(const_fn)]
 //! #![feature(proc_macro)]
 //! #![no_std]
 //! 
@@ -60,8 +59,11 @@
 //!     // As this task runs at lower priority it needs a critical section to
 //!     // prevent `sys_tick` from preempting it while it modifies this resource
 //!     // data. The critical section is required to prevent data races which can
-//!     // lead to undefined behavior
-//!     r.COUNTER.claim_mut(t, |counter, _t| { **counter += 1; });
+//!     // lead to undefined behavior.
+//!     r.COUNTER.claim_mut(t, |counter, _t| {
+//!         // `claim_mut` creates a critical section
+//!         **counter += 1;
+//!     });
 //! 
 //!     // ..
 //! }