diff --git a/src/doc/index.md b/src/doc/index.md
index 982e24ef69549..1f262b360e3ed 100644
--- a/src/doc/index.md
+++ b/src/doc/index.md
@@ -28,6 +28,7 @@ Rust provides a number of book-length sets of documentation, collectively
 nicknamed 'The Rust Bookshelf.'
 
 * [The Rust Programming Language][book] teaches you how to program in Rust.
+* [The Unstable Book][unstable-book] has documentation for unstable features.
 * [The Rustonomicon][nomicon] is your guidebook to the dark arts of unsafe Rust.
 * [The Reference][ref] is not a formal spec, but is more detailed and comprehensive than the book.
 
@@ -44,4 +45,5 @@ landed before then. That work is being tracked [here][38643].
 [err]: error-index.html
 [book]: book/index.html
 [nomicon]: nomicon/index.html
+[unstable-book]: unstable-book/index.html