diff --git a/book/_toc.yml b/book/_toc.yml
index 24db80b..78206df 100644
--- a/book/_toc.yml
+++ b/book/_toc.yml
@@ -50,6 +50,7 @@ parts:
       - file: external/Sphinx-TUDelft-theme/README.md
       - file: external/teachbooks-sphinx-tippy/README.md
       - file: features/interactive_element.ipynb
+      - file: features/custom-launch-button.md
         sections:
         - file: external/Sphinx-Grasple-public/README.md
         - file: features/h5p.md