diff --git a/tox.ini b/tox.ini
index dbd6d51fa..c1d23b69f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -6,7 +6,7 @@
 # acme and letsencrypt are not yet on pypi, so when Tox invokes
 # "install *.zip", it will not find deps
 skipsdist = true
-envlist = py26,py27,py33,py34,py35,cover,lint
+envlist = py{26,27,33,34,35},cover,lint
 
 # nosetest -v => more verbose output, allows to detect busy waiting
 # loops, especially on Travis