diff --git a/circle.yml b/circle.yml
index 94e3491a..d534ab91 100644
--- a/circle.yml
+++ b/circle.yml
@@ -1,4 +1,9 @@
+machine:
+  post:
+    - pyenv local 2.7.11 3.3.6 3.4.4 3.5.1
+
 dependencies:
   override:
     - pip install tox tox-pyenv
-    - pyenv local 2.7.9 3.4.3 3.5.0
+  pre:
+    - pip install psutil
diff --git a/requirements.txt b/requirements.txt
index f581d1b8..ec31d5b8 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1 +1 @@
-psutil==4.2.0
+psutil==4.3.0