diff --git a/pyproject.toml b/pyproject.toml
index 1b7569bd7..05f162a50 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -67,7 +67,7 @@ doc = [
   "sphinx-design",
   "sphinx-togglebutton",
   "jupyterlite-sphinx",
-  "sphinxcontrib-youtube",
+  "sphinxcontrib-youtube<1.4",
   "sphinx-favicon>=1.0.1",
   # Install nbsphinx in case we want to test it locally even though we can't load
   # it at the same time as MyST-NB.