diff --git a/.appveyor.yml b/.appveyor.yml
index deaf503b7..a3f83394f 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -18,8 +18,8 @@ environment:
 
 install:
   - C:\Python%PYTHON%\python.exe -m pip install -U pip setuptools
-  - C:\Python%PYTHON%\python.exe -m pip install docutils==%DOCUTILS%
-  - C:\Python%PYTHON%\python.exe -m pip install -r test-reqs.txt
+  - C:\Python%PYTHON%\python.exe -m pip install docutils==%DOCUTILS% mock
+  - C:\Python%PYTHON%\python.exe -m pip install .[test,websupport]
 
 # No automatic build, just run python tests
 build: off
diff --git a/.travis.yml b/.travis.yml
index 6df4f7cfb..73fd9c459 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -40,7 +40,8 @@ addons:
 install:
   - pip install -U pip setuptools
   - pip install docutils==$DOCUTILS
-  - pip install -r test-reqs.txt
+  - pip install .[test,websupport]
+  - pip install flake8
   - if [[ $TRAVIS_PYTHON_VERSION == '3.6' ]]; then python3.6 -m pip install mypy typed-ast; fi
 script:
   - flake8
diff --git a/CONTRIBUTING.rst b/CONTRIBUTING.rst
index eca6a01ac..7c8a90c6b 100644
--- a/CONTRIBUTING.rst
+++ b/CONTRIBUTING.rst
@@ -116,7 +116,7 @@ These are the basic steps needed to start developing on Sphinx.
 
    * Run the unit tests::
 
-       pip install -r test-reqs.txt
+       pip install .[test,websupport]
        make test
 
    * Again, it's useful to turn on deprecation warnings on so they're shown in
diff --git a/MANIFEST.in b/MANIFEST.in
index 1530c28cd..a5699c23c 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -12,7 +12,6 @@ include sphinx-autogen.py
 include sphinx-build.py
 include sphinx-quickstart.py
 include sphinx-apidoc.py
-include test-reqs.txt
 include tox.ini
 include sphinx/locale/.tx/config
 
diff --git a/setup.py b/setup.py
index cec86eed9..a4dd6b078 100644
--- a/setup.py
+++ b/setup.py
@@ -69,19 +69,19 @@ extras_require = {
     ],
     'test': [
         'pytest',
-        'mock',  # it would be better for 'test:python_version in 2.7'
-        'simplejson',  # better: 'test:platform_python_implementation=="PyPy"'
+        'pytest-cov',
         'html5lib',
     ],
+    'test:python_version<"3"': [
+        'enum34',
+        'mock',
+    ],
+    'test:python_version>="3"': [
+        'mypy',
+        'typed_ast',
+    ],
 }
 
-# for sdist installation with pip-1.5.6
-if sys.platform == 'win32':
-    requires.append('colorama>=0.3.5')
-
-if sys.version_info < (3, 5):
-    requires.append('typing')
-
 # Provide a "compile_catalog" command that also creates the translated
 # JavaScript files if Babel is available.
 
@@ -90,10 +90,7 @@ cmdclass = {}
 try:
     from babel.messages.pofile import read_po
     from babel.messages.frontend import compile_catalog
-    try:
-        from simplejson import dump
-    except ImportError:
-        from json import dump
+    from json import dump
 except ImportError:
     pass
 else:
diff --git a/test-reqs.txt b/test-reqs.txt
deleted file mode 100644
index 3a7bde8ea..000000000
--- a/test-reqs.txt
+++ /dev/null
@@ -1,20 +0,0 @@
-flake8
-pytest>=3.0
-pytest-cov
-mock
-six>=1.4
-Jinja2>=2.3
-Pygments>=2.0
-docutils>=0.11
-snowballstemmer>=1.1
-babel
-sqlalchemy>=0.9
-whoosh>=2.0
-alabaster
-sphinx_rtd_theme
-sphinxcontrib-websupport
-imagesize
-requests
-html5lib
-enum34
-typing
diff --git a/tox.ini b/tox.ini
index 519020f98..00b3c99e2 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,16 +1,15 @@
 [tox]
-envlist=flake8,py27,py34,py35,py36,pypy,du14,du13,du12,du11
+minversion=2.0
+envlist=flake8,mypy,py{27,34,35,36},pypy,du{11,12,13,14}
 
 [testenv]
 passenv = https_proxy http_proxy no_proxy
-deps=
-    six
-    pytest
-    pytest-cov
-    html5lib
-    mock
-    enum34
-    typing
+# TODO(stephenfin) Replace this with the 'extras' config option when tox 2.4 is
+# widely available, likely some time after the Ubuntu 18.04 release
+#
+# https://tox.readthedocs.io/en/latest/config.html#confval-extras=MULTI-LINE-LIST
+deps =
+    .[test,websupport]
 setenv =
     SPHINX_TEST_TEMPDIR = {envdir}/testbuild
 commands=
@@ -18,11 +17,6 @@ commands=
         --durations 25 {posargs}
     sphinx-build -q -W -b html -d {envtmpdir}/doctrees doc {envtmpdir}/html
 
-[testenv:pypy]
-deps=
-    simplejson
-    {[testenv]deps}
-
 [testenv:du11]
 deps=
     docutils==0.11
@@ -59,10 +53,6 @@ deps=
     {[testenv]deps}
 
 [testenv:py35]
-deps=
-    mypy
-    typed_ast
-    {[testenv]deps}
 commands=
     {envpython} -Wall tests/run.py --cov=sphinx --durations 25 {posargs}
     sphinx-build -q -W -b html -d {envtmpdir}/doctrees doc {envtmpdir}/html