diff --git a/book/_toc.yml b/book/_toc.yml
index 23ac43c..19b9103 100644
--- a/book/_toc.yml
+++ b/book/_toc.yml
@@ -15,6 +15,7 @@ parts:
       - file: exercises/004.md
       - file: exercises/005.md
       - file: exercises/006.md
+      - file: exercises/007.md
       - file: exercises/summary
     - file: syntax_exercises.md
       sections: