diff --git a/src/behavior-considered-undefined.md b/src/behavior-considered-undefined.md
index 7936e8aa0..612aac0c9 100644
--- a/src/behavior-considered-undefined.md
+++ b/src/behavior-considered-undefined.md
@@ -47,4 +47,4 @@ code.
 [`UnsafeCell<U>`]: https://doc.rust-lang.org/std/cell/struct.UnsafeCell.html
 [`read_unaligned`]: https://doc.rust-lang.org/std/ptr/fn.read_unaligned.html
 [`write_unaligned`]: https://doc.rust-lang.org/std/ptr/fn.write_unaligned.html
-[Rustonomicon]: ../nomicon
+[Rustonomicon]: ../nomicon/index.html