diff --git a/lower-constraints.txt b/lower-constraints.txt
index cf98877..9ffa686 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -11,6 +11,7 @@ eventlet==0.18.2
 extras==1.0.0
 fixtures==3.0.0
 flake8==2.5.5
+futures==3.1.1;python_version=='2.7' or python_version=='2.6' # PSF
 gitdb==0.6.4
 GitPython==1.0.1
 greenlet==0.4.10
diff --git a/requirements.txt b/requirements.txt
index 1b63799..ed9323c 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -11,3 +11,4 @@ cffi>=1.7.0 # MIT
 eventlet!=0.18.3,!=0.20.1,>=0.18.2 # MIT
 greenlet>=0.4.10 # MIT
 msgpack>=0.5.0 # Apache-2.0
+futures>=3.1.1;python_version=='2.7' or python_version=='2.6' # PSF