diff --git a/book/_toc.yml b/book/_toc.yml
index 8e6ddf2..f1f35d6 100644
--- a/book/_toc.yml
+++ b/book/_toc.yml
@@ -13,6 +13,7 @@ parts:
       - file: exercises/002.md
       - file: exercises/003.md
       - file: exercises/004.md
+      - file: exercises/005.md
     - file: references.md
     - file: changelog.md
     - file: credits.md