diff --git a/pyproject.toml b/pyproject.toml
index 57c5933c..67b3fe1a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -88,7 +88,7 @@ development = [
     'ruff==0.14.10',
 ]
 docs = [
-    'sphinx==8.2.3',
+    'sphinx==9.1.0',
     'sphinx-argparse==0.5.2',
     'plantweb==1.3.0',
     # 'sphinxcontrib.asciinema==0.4.2',