diff --git a/requirements-docs.txt b/requirements-docs.txt
new file mode 100644
index 00000000..a018f983
--- /dev/null
+++ b/requirements-docs.txt
@@ -0,0 +1 @@
+sphinx_autorun
diff --git a/setup.py b/setup.py
index ad4bef6c..642241d3 100644
--- a/setup.py
+++ b/setup.py
@@ -25,7 +25,7 @@
     setup_requires=['setuptools_scm', 'pytest-runner'],
     tests_require=open('requirements-dev.txt').readlines(),
     extras_require={
-        'docs': ['sphinx_autorun'],
+        'docs': open('requirements-docs.txt').readlines(),
     },
     classifiers=[
         'Development Status :: 4 - Beta',
diff --git a/tox.ini b/tox.ini
index c0617a7a..c7c98b35 100644
--- a/tox.ini
+++ b/tox.ini
@@ -20,10 +20,11 @@ commands = flake8
 
 [testenv:docs]
 basepython = python3
-extras = docs
 whitelist_externals =
   make
+# These two steps imitate RTD as best as possible.
 commands =
+  pip install -rrequirements-docs.txt
   make -C docs html
 
 [flake8]