diff --git a/doc/source/configuration.rst b/doc/source/configuration.rst
index 2787198..765e66b 100644
--- a/doc/source/configuration.rst
+++ b/doc/source/configuration.rst
@@ -1,8 +1,9 @@
 Configuration
 =============
 
-To enable the ironic-prometheus-exporter to collect the sensor data from Ironic,
-it's necessary to enable some configuration parameters in the ``ironic.conf``.
+To enable the ironic-prometheus-exporter to collect the sensor data from
+Ironic, it's necessary to enable some configuration parameters in the
+``ironic.conf``.
 Below you can see an example of the required configuration, the table
 :ref:`ipe_conf` shows all the available configuration options.
 
@@ -24,7 +25,8 @@ Example of configuration
 
 .. _ipe_conf:
 
-.. list-table:: Configuration options for the ironic-prometheus-exporter in Ironic
+.. list-table:: Configuration options for the ironic-prometheus-exporter
+   in Ironic
    :widths: 15 15 10 50 10
    :header-rows: 1
 
@@ -70,5 +72,5 @@ Example of configuration
 
 
 .. note::
-   After doing the modifications in the ``ironic.conf`` don't forget to re-start
-   the ironic-conductor service
+   After doing the modifications in the ``ironic.conf`` don't forget to
+   re-start the ironic-conductor service
diff --git a/doc/source/install.rst b/doc/source/install.rst
index 9290cc0..1c69c12 100644
--- a/doc/source/install.rst
+++ b/doc/source/install.rst
@@ -35,5 +35,8 @@ on RDO.
    $ pip install entry_point_inspector --user <user>
    $ epi group show oslo.messaging.notify.drivers
 
-- Output in case of a successful installation: `prometheus_exporter` is listed in the `Name` column and the `Error` column should be empty.
-- Output in case of an unsuccessful installation: `prometheus_exporter` is listed in the `Name` column and the `Error` column will have more information.
+- Output in case of a successful installation: `prometheus_exporter` is listed
+  in the `Name` column and the `Error` column should be empty.
+- Output in case of an unsuccessful installation: `prometheus_exporter` is
+  listed in the `Name` column and the `Error` column will have more
+  information.
diff --git a/test-requirements.txt b/test-requirements.txt
index f9aa534..54ae677 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -1,9 +1,4 @@
-hacking>=3.1.0,<4.0.0 # Apache-2.0
 
-flake8
-flake8-import-order>=0.17.1
 stestr>=2.0.0 # Apache-2.0
 oslotest>=3.2.0 # Apache-2.0
 coverage!=4.4,>=4.0 # Apache-2.0
-pycodestyle>=2.0.0,<2.7.0 # MIT
-
diff --git a/tox.ini b/tox.ini
index 41f5fe2..9945c46 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-minversion = 3.2.1
+minversion = 3.9.0
 envlist = py3,pep8
 skipsdist = True
 ignore_basepython_conflict=true
@@ -20,12 +20,18 @@ deps  =
 commands = stestr run {posargs}
 
 [testenv:pep8]
-commands = flake8 {posargs}
+deps =
+    hacking>=3.1.0,<4.0.0 # Apache-2.0
+    doc8>=0.8.1 # Apache-2.0
+    flake8-import-order>=0.17.1 # LGPLv3
+    pycodestyle>=2.0.0,<2.7.0 # MIT
+commands =
+    flake8 {posargs}
+    doc8 README.rst CONTRIBUTING.md doc/source
 
 [testenv:cover]
 setenv =
     PYTHON=coverage run --parallel-mode
-
 commands =
   coverage erase
   stestr run {posargs}