diff --git a/library/alloc/src/io/buffered/mod.rs b/library/alloc/src/io/buffered/mod.rs
index 1bddcfb801932..795a918b88533 100644
--- a/library/alloc/src/io/buffered/mod.rs
+++ b/library/alloc/src/io/buffered/mod.rs
@@ -132,6 +132,7 @@ impl<W> IntoInnerError<W> {
     /// obtain ownership of the underlying error.
     ///
     /// # Example
+    ///
     /// ```
     /// use std::io::{BufWriter, ErrorKind, Write};
     ///
@@ -154,6 +155,7 @@ impl<W> IntoInnerError<W> {
     /// advanced error recovery.
     ///
     /// # Example
+    ///
     /// ```
     /// use std::io::{BufWriter, ErrorKind, Write};
     ///
diff --git a/library/alloc/src/io/prelude.rs b/library/alloc/src/io/prelude.rs
index 86ae040d1d6f6..d3ebc373e6284 100644
--- a/library/alloc/src/io/prelude.rs
+++ b/library/alloc/src/io/prelude.rs
@@ -4,8 +4,9 @@
 //! by adding a glob import to the top of I/O heavy modules:
 //!
 //! ```
+//! # #![feature(alloc_io)]
 //! # #![allow(unused_imports)]
-//! use std::io::prelude::*;
+//! use alloc::io::prelude::*;
 //! ```
 
 #[stable(feature = "rust1", since = "1.0.0")]
diff --git a/library/core/src/io/error.rs b/library/core/src/io/error.rs
index 61abdb16d07da..60b798e69ae6e 100644
--- a/library/core/src/io/error.rs
+++ b/library/core/src/io/error.rs
@@ -1115,6 +1115,7 @@ impl fmt::Display for ErrorKind {
     /// This is similar to `impl Display for Error`, but doesn't require first converting to Error.
     ///
     /// # Examples
+    ///
     /// ```
     /// use core::io::ErrorKind;
     /// assert_eq!("entity not found", ErrorKind::NotFound.to_string());
diff --git a/library/core/src/io/prelude.rs b/library/core/src/io/prelude.rs
index 15dacaa3a4fa0..3ff5833fb6331 100644
--- a/library/core/src/io/prelude.rs
+++ b/library/core/src/io/prelude.rs
@@ -4,8 +4,9 @@
 //! by adding a glob import to the top of I/O heavy modules:
 //!
 //! ```
+//! # #![feature(core_io)]
 //! # #![allow(unused_imports)]
-//! use std::io::prelude::*;
+//! use core::io::prelude::*;
 //! ```
 
 #[stable(feature = "rust1", since = "1.0.0")]