diff --git a/tox.ini b/tox.ini
index 9dce5e49..e92a0a3f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -50,6 +50,7 @@ commands = {posargs}
 
 #set PYTHONHASHSEED=0 to prevent wsmeext.sphinxext from randomly failing.
 [testenv:docs]
+basepython = python2.7
 setenv = PYTHONHASHSEED=0
 commands = python setup.py build_sphinx