diff --git a/doc/requirements.txt b/doc/requirements.txt
index f8737ab..390e23d 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -3,7 +3,7 @@
 # process, which may cause wedges in the gate later.
 # These are needed for docs generation
 openstackdocstheme>=1.20.0 # Apache-2.0
-sphinx!=1.6.6,!=1.6.7,>=1.6.2,<2.0.0;python_version=='2.7' # BSD
-sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.2;python_version>='3.4' # BSD
+sphinx>=1.8.0,<2.0.0;python_version=='2.7' # BSD
+sphinx>=1.8.0,!=2.1.0;python_version>='3.4' # BSD
 reno>=2.5.0 # Apache-2.0
 fixtures>=3.0.0 # Apache-2.0/BSD
diff --git a/tox.ini b/tox.ini
index 467cce0..2da179e 100644
--- a/tox.ini
+++ b/tox.ini
@@ -27,8 +27,12 @@ commands = {posargs}
 
 [testenv:docs]
 basepython = python3
+whitelist_externals =
+  rm
 deps = -r{toxinidir}/doc/requirements.txt
-commands = sphinx-build -W -b html doc/source doc/build/html
+commands =
+  rm -fr doc/build
+  sphinx-build -W --keep-going -b html doc/source doc/build/html
 
 [testenv:cover]
 basepython = python3
@@ -46,8 +50,12 @@ import_exceptions = oslo_middleware._i18n
 
 [testenv:releasenotes]
 basepython = python3
+whitelist_externals =
+  rm
 deps = -r{toxinidir}/doc/requirements.txt
-commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
+commands =
+  rm -rf releasenotes/build
+  sphinx-build -a -E -W -d releasenotes/build/doctrees --keep-going -b html releasenotes/source releasenotes/build/html
 
 [testenv:lower-constraints]
 basepython = python3