diff --git a/src/doc/unstable-book/src/SUMMARY.md b/src/doc/unstable-book/src/SUMMARY.md
index 5fb323d6ce909..44eda204a3d29 100644
--- a/src/doc/unstable-book/src/SUMMARY.md
+++ b/src/doc/unstable-book/src/SUMMARY.md
@@ -75,6 +75,7 @@
 - [simd](simd.md)
 - [simd_ffi](simd-ffi.md)
 - [slice_patterns](slice-patterns.md)
+- [sort_unstable](sort-unstable.md)
 - [specialization](specialization.md)
 - [staged_api](staged-api.md)
 - [start](start.md)
diff --git a/src/doc/unstable-book/src/sort-unstable.md b/src/doc/unstable-book/src/sort-unstable.md
new file mode 100644
index 0000000000000..aec39de2c9a73
--- /dev/null
+++ b/src/doc/unstable-book/src/sort-unstable.md
@@ -0,0 +1,9 @@
+# `sort_unstable`
+
+The tracking issue for this feature is: [#40585]
+
+[#40585]: https://github.com/rust-lang/rust/issues/40585
+
+------------------------
+
+