diff --git a/doc/requirements.txt b/doc/requirements.txt
new file mode 100644
index 00000000..3180aac3
--- /dev/null
+++ b/doc/requirements.txt
@@ -0,0 +1,10 @@
+# The order of packages is significant, because pip processes them in the order
+# of appearance. Changing the order has an impact on the overall integration
+# process, which may cause wedges in the gate later.
+
+sphinx!=1.6.6,!=1.6.7,>=1.6.2 # BSD
+openstackdocstheme>=1.31.2 # Apache-2.0
+sphinx_rtd_theme
+
+# releasenotes
+reno>=2.5.0 # Apache-2.0
diff --git a/tox.ini b/tox.ini
index 0291fa5a..7253154d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,10 +1,9 @@
 [tox]
-minversion = 1.6
-envlist = docs,py37,pep8
+minversion = 4.0.2
+envlist = py3,pep8
 skipsdist = True
 
 [testenv]
-basepython = python3
 usedevelop = True
 setenv = VIRTUAL_ENV={envdir}
 deps =
@@ -17,7 +16,6 @@ commands = stestr run --slowest {posargs}
 commands = flake8 {posargs}
 
 [testenv:cover]
-basepython = python3
 setenv =
   {[testenv]setenv}
   PYTHON=coverage run --source cloudbaseinit --parallel-mode
@@ -29,21 +27,20 @@ commands =
   coverage xml -o cover/coverage.xml
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
-[testenv:releasenotes]
-basepython = python3
-commands =
-  sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
-
 [testenv:docs]
-basepython = python3
 deps =
-  sphinx_rtd_theme
+  -r{toxinidir}/doc/requirements.txt
+  -egit+https://github.com/openstack/cloudbase-init\#egg=cloudbase-init
 commands =
   sphinx-build -a -E -W -d doc/build/doctrees -b html doc/source doc/build/html
 
+[testenv:releasenotes]
+deps = {[testenv:docs]deps}
+commands =
+  sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
+
 [flake8]
 # E125 is deliberately excluded. See https://github.com/jcrocholl/pep8/issues/126
 # E251 Skipped due to https://github.com/jcrocholl/pep8/issues/301