diff --git a/tox.ini b/tox.ini
index 86dd2302daf9d53ad0e56e9f096091488f8d318b..06a7bca5ee7dabf94495faf231087d85362f7ca4 100644
--- a/tox.ini
+++ b/tox.ini
@@ -14,6 +14,17 @@ deps=pytest>=2.8.3
 commands=
   py.test
 
+[testenv:py26]
+# versions still supporting py26.
+deps=
+  pytest==3.2.5
+  setuptools==36.8.0
+
+[testenv:py33]
+# versions still supporting py33.
+deps=
+  pytest==3.2.5
+
 [testenv:flake8]
 deps=flake8
 commands=flake8 diceware tests setup.py