diff --git a/requirements.txt b/requirements.txt
index aaae7f2..90deb40 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,4 +3,6 @@ sphinx-inline-tabs == 2023.4.21
 
 git+https://github.com/TeachBooks/TeachBooks-Favourites
 
+teachbooks-sphinx-grasple
+
 docutils==0.17.1