diff --git a/tox.ini b/tox.ini
index 911a5a1..55e573d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -6,6 +6,7 @@ envlist = docs,py27,pep8
 skipsdist = True
 
 [testenv]
+basepython=python3
 usedevelop = True
 setenv = VIRTUAL_ENV={envdir}
 install_command = pip install -U {opts} {packages}