diff --git a/requirements.txt b/requirements.txt
index 1c62a75..23cb0f3 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,5 @@
 # Version is fixed in the GitLab runner for building documentation
-sphinx==5.3.0
+sphinx==9.1.0
 sphinx-intl==2.3.1
 sphinx-rtd-theme
 Jinja2==3.1.6