diff --git a/requirements/bob-requirements.txt b/requirements/bob-requirements.txt
index 247d18c2..099f1afe 100644
--- a/requirements/bob-requirements.txt
+++ b/requirements/bob-requirements.txt
@@ -19,3 +19,4 @@ plotly
 # pytest
 pytest
 pytest-cov
+tornado>=6.4.2 # not directly required, pinned by Snyk to avoid a vulnerability