diff --git a/packages/python/plotly/test_requirements/requirements_37_optional.txt b/packages/python/plotly/test_requirements/requirements_37_optional.txt
index 8c33824da66..6c8fc903938 100644
--- a/packages/python/plotly/test_requirements/requirements_37_optional.txt
+++ b/packages/python/plotly/test_requirements/requirements_37_optional.txt
@@ -19,3 +19,4 @@ matplotlib==2.2.3
 scikit-image==0.14.4
 psutil==5.7.0
 kaleido
+tornado>=6.4.2 # not directly required, pinned by Snyk to avoid a vulnerability