diff --git a/doc/requirements.txt b/doc/requirements.txt
new file mode 100644
index 0000000..7ddda55
--- /dev/null
+++ b/doc/requirements.txt
@@ -0,0 +1,5 @@
+sphinx>=1.8.0,!=2.1.0;python_version>='3.4' # BSD
+sphinxcontrib-httpdomain>=1.3.0 # BSD
+sphinxcontrib-pecanwsme>=0.8.0 # Apache-2.0
+openstackdocstheme>=1.30.0 # Apache-2.0
+reno>=2.5.0 # Apache-2.0
diff --git a/doc/source/contributor/creating_custom_actions.rst b/doc/source/contributor/creating_custom_actions.rst
index fa63e96..23ba57d 100644
--- a/doc/source/contributor/creating_custom_actions.rst
+++ b/doc/source/contributor/creating_custom_actions.rst
@@ -34,7 +34,8 @@ How to write a Custom Action
    mistral.actions =
        example.runner = my.mistral_plugins.somefile:RunnerAction
 
-3. Reinstall your library package if it was installed in system (not in virtualenv).
+3. Reinstall your library package if it was installed in system
+   (not in virtualenv).
 
 4. Run db-sync tool to ensure your actions are in Mistral's database
 
diff --git a/lower-constraints.txt b/lower-constraints.txt
index 7f5846f..6690033 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -4,6 +4,7 @@ Babel==2.3.4
 coverage==4.0
 debtcollector==1.2.0
 docutils==0.11
+doc8==0.6.0
 dulwich==0.15.0
 eventlet==0.20.0
 extras==1.0.0
diff --git a/test-requirements.txt b/test-requirements.txt
index ff76531..5d5d532 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -3,12 +3,10 @@
 # process, which may cause wedges in the gate later.
 
 hacking>=1.1.0 # Apache-2.0
+doc8>=0.6.0 # Apache-2.0
+Pygments>=2.2.0 # BSD license
 coverage!=4.4,>=4.0 # Apache-2.0
-sphinx>=1.8.0,<2.0.0;python_version=='2.7' # BSD
-sphinx>=1.8.0,!=2.1.0;python_version>='3.4' # BSD
-openstackdocstheme>=1.18.1 # Apache-2.0
 oslotest>=3.2.0 # Apache-2.0
 stestr>=2.0.0 # Apache-2.0
 testtools>=2.2.0 # MIT
-# releasenotes
-reno>=2.5.0 # Apache-2.0
+
diff --git a/tox.ini b/tox.ini
index 58f642f..e24ca85 100644
--- a/tox.ini
+++ b/tox.ini
@@ -25,7 +25,7 @@ whitelist_externals =
 
 [testenv:pep8]
 commands =
-    python setup.py check --restructuredtext --strict
+    doc8 doc/source
     flake8 {posargs}
 
 [testenv:venv]
@@ -41,11 +41,13 @@ commands =
     coverage xml -o cover/coverage.xml
 
 [testenv:docs]
-commands = python setup.py build_sphinx
+deps = -r{toxinidir}/doc/requirements.txt
+setenv = PYTHONHASHSEED=0
+commands =
+  rm -rf doc/build
+  sphinx-build -E -W --keep-going -b html doc/source doc/build/html
 
 [testenv:releasenotes]
-whitelist_externals =
-  rm
 commands =
   rm -rf releasenotes/build
   sphinx-build -a -E -W -d releasenotes/build/doctrees --keep-going -b html releasenotes/source releasenotes/build/html
@@ -54,9 +56,13 @@ commands =
 whitelist_externals = oslo_debug_helper
 commands = oslo_debug_helper -t mistral_lib/tests {posargs}
 
+[doc8]
+extensions = .rst, .yaml, .mistral
+# Maximal line length should be 80.
+max-line-length = 80
+
 [flake8]
 # E123, E125 skipped as they are invalid PEP-8.
-
 show-source = True
 ignore = E123,E125,W504
 builtins = _