diff --git a/CONTRIBUTING.rst b/CONTRIBUTING.rst
index 22b9e9d0..bd35c0b5 100644
--- a/CONTRIBUTING.rst
+++ b/CONTRIBUTING.rst
@@ -121,7 +121,7 @@ Contributions to the documentation are welcome. Documentation is written in `reS
 
 To build the docs in "watch" mode: ::
 
-   $ tox -e watch-docs
+   $ tox -e docs-serve
 
 Changes in the `docs/` directory will automatically trigger a rebuild.
 
diff --git a/pyproject.toml b/pyproject.toml
index f8105b5f..07c1224a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -76,7 +76,7 @@ tests = [
 ]
 docs = [
   "webargs[frameworks]",
-  "Sphinx==8.2.3",
+  "Sphinx==9.1.0",
   "sphinx-issues==5.0.1",
   "furo==2025.12.19",
 ]
diff --git a/tox.ini b/tox.ini
index c9c91879..3ef6c592 100644
--- a/tox.ini
+++ b/tox.ini
@@ -40,13 +40,13 @@ commands = sphinx-build docs/ docs/_build {posargs}
 
 ; Below tasks are for development only (not run in CI)
 
-[testenv:watch-docs]
-deps =
-  sphinx-autobuild
+[testenv:docs-serve]
+deps = sphinx-autobuild
 extras = docs
-commands = sphinx-autobuild --open-browser docs/ docs/_build {posargs} --watch src/webargs --delay 2
+commands = sphinx-autobuild --port=0 --open-browser --delay=2 docs/ docs/_build {posargs} --watch src --watch CONTRIBUTING.rst --watch README.rst
 
-[testenv:watch-readme]
+[testenv:readme-serve]
 deps = restview
 skip_install = true
 commands = restview README.rst
+