diff --git a/snapshot_requirements.txt b/snapshot_requirements.txt
index 8c4680f..3098823 100644
--- a/snapshot_requirements.txt
+++ b/snapshot_requirements.txt
@@ -97,7 +97,7 @@ rsa==4.0
 scikit-learn==0.21.3
 scipy==1.3.0
 -e git+git@github.com:howl-anderson/seq2annotation.git@faeec18f16b73a28dc323572f416341b2c1ac7ed#egg=seq2annotation
-six==1.12.0
+six==1.15.0
 sympy==1.4
 tensor2tensor==1.13.4
 tensorboard==1.15.0