diff --git a/setup.py b/setup.py
index 1887620bd6..4a91bfb0ef 100644
--- a/setup.py
+++ b/setup.py
@@ -32,7 +32,7 @@
 tensorboard_extra_require = [
     "tensorflow-cpu>=2.3.0, <=2.5.0",
     "grpcio~=1.34.0",
-    "six~=1.16.0",
+    "six~=1.15.0",
 ]
 metadata_extra_require = ["pandas >= 1.0.0"]
 full_extra_require = tensorboard_extra_require + metadata_extra_require