diff --git a/requirements-doc.txt b/requirements-doc.txt
index 96f8f798..1de0ac90 100644
--- a/requirements-doc.txt
+++ b/requirements-doc.txt
@@ -4,7 +4,7 @@ matplotlib
 # document requirements
 pandoc
 Jinja2
-sphinx>=9.0.4
+sphinx>=9.1.1
 myst-nb
 sphinx_thebe
 sphinx-book-theme>=1.2.0