diff --git a/lower-constraints.txt b/lower-constraints.txt
index d2cee79..084a637 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -43,7 +43,6 @@ PyYAML==3.12
 reno==2.5.0
 requests==2.18.0
 requestsexceptions==1.2.0
-six==1.10.0
 snowballstemmer==1.2.1
 Sphinx==1.8.0
 sphinxcontrib-websupport==1.0.1