diff --git a/pyproject.toml b/pyproject.toml
index 1c85e162..df4b4239 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -65,7 +65,7 @@ dev = [
   "mypy==v1.4.1 ; python_version>='3.7' and python_version<'3.8'",
   "mypy==v1.13.0 ; python_version>='3.8'",
   # Docs.
-  "Sphinx==7.3.7 ; python_version>='3.9'",
+  "Sphinx==8.1.3 ; python_version>='3.9'",
   "sphinx-rtd-theme==3.0.2 ; python_version>='3.9'",
 ]