Revert sphinx pin
diff --git a/dev-requirements.txt b/dev-requirements.txt
index c409ff9..b33b5e6 100644
--- a/dev-requirements.txt
+++ b/dev-requirements.txt
@@ -9,7 +9,7 @@
 pyasn1_modules
 pytest
 requests
-sphinx==1.3.1
+sphinx
 sphinx_rtd_theme
 sphinxcontrib-spelling
 tox
diff --git a/tox.ini b/tox.ini
index dfb6761..6ad8285 100644
--- a/tox.ini
+++ b/tox.ini
@@ -27,7 +27,7 @@
     doc8
     pyenchant
     readme_renderer
-    sphinx==1.3.1
+    sphinx
     sphinx_rtd_theme
     sphinxcontrib-spelling
 basepython = python2.7