diff --git a/docs/requirements.txt b/docs/requirements.txt
index b4c11c9..de55921 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,4 +1,4 @@
-sphinx
+sphinx==4.5.0
 docutils
 git+https://github.com/f4pga/sphinx_f4pga_theme.git@f4pga#egg=sphinx-f4pga-theme
 sphinx-tabs