diff --git a/tox.ini b/tox.ini
index 938e5c3..48137d5 100644
--- a/tox.ini
+++ b/tox.ini
@@ -2,10 +2,10 @@
 envlist = py26, py27, py34, pypy, style, docs
 
 [testenv]
-setenv =
-    PYTHONPATH = {toxinidir}:{toxinidir}/json_config
 commands =
     {posargs:{envpython} setup.py test}
+basepython= python2.7
+setenv=PYTHONWARNINGS=all
 
 [testenv:style]
 deps =