diff --git a/setup.py b/setup.py
index 5d13b576..6a4f2ac4 100644
--- a/setup.py
+++ b/setup.py
@@ -34,7 +34,7 @@
     "google-auth >= 1.21.1, < 2.0dev",
     "requests >= 2.18.0, < 3.0.0dev",
     "setuptools >= 34.0.0",
-    "six >= 1.10.0",
+    "six >= 1.13.0",
     "pytz",
     'futures >= 3.2.0; python_version < "3.2"',
 ]