diff --git a/book/features/favourites.md b/book/features/favourites.md
index 61b3da5..2465fe6 100644
--- a/book/features/favourites.md
+++ b/book/features/favourites.md
@@ -30,6 +30,8 @@ TeachBooks Favourites is a Sphinx extension which collects all of TeachBooks' fa
 - [Notebook execution patterns](../_git/github.com_TeachBooks_Sphinx-NB-Execution-Patterns/Manual/README.md)
 - [Sphinx Launch Buttons](../external/Sphinx-launch-buttons/README.md)
 
+The extension [Open in new tab](https://pypi.org/project/sphinx-new-tab-link/) is nice, but is not compatible with all setups (dependency clash) so is not included in TeachBooks-Favourites. 
+
 All features which are part of TeachBooks Favourites are include the following label on their respective pages in this manual: {bdg-primary-line}`Part of TeachBooks Favourites`. If you'd like to use specific features, but not the entire TeachBooks Favourites, you can remove this extension and replace it with the individual extensions you want to use.
 
 ## Installation