diff --git a/tox.ini b/tox.ini
index d312d51..7572850 100644
--- a/tox.ini
+++ b/tox.ini
@@ -13,7 +13,8 @@
 ; limitations under the License.
 
 [tox]
-envlist = py27
+envlist = py27,py35,py36
+skip_missing_interpreters = true
 
 [testenv]
 commands =