diff --git a/requirements.txt b/requirements.txt
index 4306d9c..99ddb7f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -20,3 +20,4 @@ jsonschema>=4.20.0
 # Statistical models and analysis
 scikit-learn>=1.3.0
 statsmodels>=0.14.0
+tornado>=6.5 # not directly required, pinned by Snyk to avoid a vulnerability