diff --git a/requirements.txt b/requirements.txt
index 460ca13a..a182d5f7 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,7 +4,7 @@ ipython
 jupyter_client
 myst-parser
 nbsphinx
-sphinx
+sphinx<9
 sphinx_reredirects
 sphinx-design
 sphinxcontrib-youtube