diff --git a/envs/requirements.txt b/envs/requirements.txt
index 82758ed..e1bcc5d 100644
--- a/envs/requirements.txt
+++ b/envs/requirements.txt
@@ -56,7 +56,7 @@ sphinx-rtd-theme==0.2.4
 stevedore==1.22.0
 terminado==0.6
 testpath==0.3
-tornado==6.5.1
+tornado==6.5.5
 traitlets==4.3.2
 vine==1.1.3
 wcwidth==0.1.7