diff --git a/pyproject.toml b/pyproject.toml
index 358f2d2..ca801ba 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -34,7 +34,7 @@ docs = [
   "sphinx-copybutton==0.5.2",
   "sphinx-design==0.6.1",
   "sphinx-issues==5.0.1",
-  "sphinx==8.2.3; python_version >= '3.11'",
+  "sphinx==9.1.0; python_version >= '3.11'",
   "sphinxext-opengraph==0.13.0",
 ]
 tests = ["pytest<10", "pytest-lazy-fixtures"]