diff --git a/requirements.txt b/requirements.txt
index ffe2fce..dde8185 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1 +1 @@
-six
+six>=1.9.0
diff --git a/setup.py b/setup.py
index 07416e3..353894e 100644
--- a/setup.py
+++ b/setup.py
@@ -1,4 +1,4 @@
-version = '3.0.4'
+version = '3.1.4'
 
 from setuptools import setup