diff --git a/circle.yml b/circle.yml
index b00ae634..fa03dd65 100644
--- a/circle.yml
+++ b/circle.yml
@@ -2,10 +2,10 @@ machine:
     python:
         version: 2.7
     environment:
-        - TOX_ENV=docs
-        - TOX_ENV=lint
-        - TOX_ENV=py26
-        - TOX_ENV=py27
+        TOX_ENV: docs
+        TOX_ENV: lint
+        TOX_ENV: py26
+        TOX_ENV: py27
 
 dependencies:
     pre: