diff --git a/requirements_mapping.txt b/requirements_mapping.txt
index 1990a05a..5d4a86a4 100644
--- a/requirements_mapping.txt
+++ b/requirements_mapping.txt
@@ -42,7 +42,7 @@ pytz==2020.4
 PyYAML==5.4
 Shapely==1.7.1
 six==1.15.0
-tornado==6.5.1
+tornado==6.4.2
 traitlets
 typing-extensions==3.7.4.3
 wcwidth==0.2.5