diff --git a/tox.ini b/tox.ini
index 51779d871..95a877274 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,14 @@
 [tox]
-envlist=py26
+envlist=du06,du05
 
 [testenv]
 deps=nose
-commands=nosetests
+commands=
+    nosetests
+    sphinx-build -W -b html -d {envtmpdir}/doctrees doc {envtmpdir}/html
+
+[testenv:du05]
+deps=docutils==0.5
+
+[testenv:du06]
+deps=docutils==0.6