diff --git a/docs/source/command_ref.rst b/docs/source/command_ref.rst
index eadb850..50997e7 100644
--- a/docs/source/command_ref.rst
+++ b/docs/source/command_ref.rst
@@ -57,7 +57,7 @@ installed.
    * :ref:`scripts-postmkvirtualenv`
    * `requirements file format`_
 
-.. _requirements file format: https://pip.pypa.io/en/latest/reference/pip_install/#requirements-file-format
+.. _requirements file format: https://pip.pypa.io/en/stable/reference/requirements-file-format/
 
 .. _command-mktmpenv:
 
diff --git a/docs/source/developers.rst b/docs/source/developers.rst
index 01e9e04..1c6c7d7 100644
--- a/docs/source/developers.rst
+++ b/docs/source/developers.rst
@@ -98,7 +98,7 @@ the ``tests`` directory.
 
 .. _shunit2: https://github.com/kward/shunit2
 
-.. _tox: https://tox.testrun.org/
+.. _tox: https://tox.wiki/
 
 .. _developer-templates:
 
diff --git a/docs/source/plugins.rst b/docs/source/plugins.rst
index 63e8e0c..c601dbd 100644
--- a/docs/source/plugins.rst
+++ b/docs/source/plugins.rst
@@ -186,8 +186,7 @@ used).
 
 .. seealso::
 
-  * `namespace packages <https://setuptools.readthedocs.io/en/latest/setuptools.html#namespace-packages>`__
-  * `Extensible Applications and Frameworks <https://setuptools.readthedocs.io/en/latest/setuptools.html#extensible-applications-and-frameworks>`__
+  * `namespace packages <https://packaging.python.org/en/latest/guides/packaging-namespace-packages/>`__
 
 The Hook Loader
 ---------------
@@ -257,7 +256,7 @@ messages.
 .. seealso::
 
    * `Standard library documentation for logging <https://docs.python.org/library/logging.html>`__
-   * `PyMOTW for logging <https://www.doughellmann.com/PyMOTW/logging/>`__
+   * `PyMOTW for logging <http://pymotw.com/3/logging/>`__
 
 .. _plugins-extension-points:
 
diff --git a/docs/source/tips.rst b/docs/source/tips.rst
index c32bdf9..aec51f5 100644
--- a/docs/source/tips.rst
+++ b/docs/source/tips.rst
@@ -19,7 +19,7 @@ While the virtualenv ``activate`` script does attempt to provide
 an indicator in the prompt, it has various shortcomings, and
 cannot be customized.
 
-However, it does also set a shell variable named 
+However, it does also set a shell variable named
 ``VIRTUAL_ENV`` which can be used as the basis for disabling the
 built-in prompt indicator and substituting an improved one,
 as a customization to ``.bashrc`` or ``.zshrc``::
@@ -27,7 +27,7 @@ as a customization to ``.bashrc`` or ``.zshrc``::
     virtualenv_prompt() {
         # If not in a virtualenv, print nothing
         [[ "$VIRTUAL_ENV" == "" ]] && return
-    
+
         # Distinguish between the shell where the virtualenv was activated
         # and its children
         local venv_name="${VIRTUAL_ENV##*/}"
@@ -37,7 +37,7 @@ as a customization to ``.bashrc`` or ``.zshrc``::
             echo "<${venv_name}> "
         fi
     }
-    
+
     # Display a "we are in a virtualenv" indicator that works in child shells too
     VIRTUAL_ENV_DISABLE_PROMPT=1
     PS1='$(virtualenv_prompt)'"$PS1"
@@ -116,10 +116,6 @@ directory each time he runs ``cd``.  If it finds a ``.venv`` file, it
 activates the environment named within.  On leaving that directory,
 the current virtualenv is automatically deactivated.
 
-`Harry Marr <http://hmarr.com/about/>`__
-wrote a similar function that works with `git repositories
-<http://hmarr.com/2010/jan/19/making-virtualenv-play-nice-with-git/>`__.
-
 Installing Common Tools Automatically in New Environments
 =========================================================
 
diff --git a/setup.cfg b/setup.cfg
index 0ec5d5c..764868c 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -14,7 +14,7 @@ classifier =
     Programming Language :: Python :: 3.9
     Programming Language :: Python :: 3.10
     Programming Language :: Python :: 3.11
-Intended Audience :: Developers
+    Intended Audience :: Developers
     Environment :: Console
 keywords =
     virtualenv
diff --git a/tox.ini b/tox.ini
index c97b5ef..b629574 100644
--- a/tox.ini
+++ b/tox.ini
@@ -42,7 +42,9 @@ commands =  ksh ./tests/run_tests {envdir} []
 deps =
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/docs/requirements.txt
-commands = python setup.py build_sphinx
+commands =
+    sphinx-build -W -j auto -b html -d docs/build/doctrees docs/source docs/build/html
+    sphinx-build -W -j auto -b linkcheck -d docs/build/doctrees docs/source docs/build/linkcheck
 
 [testenv:pkglint]
 deps=