diff --git a/src/buffer.rs b/src/buffer.rs
index 420b034..cc05485 100644
--- a/src/buffer.rs
+++ b/src/buffer.rs
@@ -22,7 +22,7 @@
 //! using Syn's parser combinator macros.
 //!
 //! ```
-//! #![feature(proc_macro)]
+//! #![feature(proc_macro_diagnostic)]
 //!
 //! extern crate syn;
 //! extern crate proc_macro;