diff --git a/requirements.txt b/requirements.txt
index 7387278..4a98a28 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -17,7 +17,7 @@ docutils==0.14
 enum34==1.1.6
 funcsigs==1.0.2
 future==0.16.0
-futures==3.2.0
+futures==3.1.1
 idna==2.6
 imagesize==1.0.0
 ipaddress==1.0.17