diff --git a/tox.ini b/tox.ini
index 570b470..8a51e64 100644
--- a/tox.ini
+++ b/tox.ini
@@ -35,6 +35,6 @@ commands = nosetests --with-html --html-file=system.html --verbose {posargs:test
 [testenv:docs]
 changedir = docs
 deps =
-    sphinx
+    sphinx != 1.5
     sphinx_rtd_theme
 commands = sphinx-build -W -b html -d _build/html/doctrees . _build/html