diff --git a/online-inference/custom-sentiment/custom-predictor/requirements.txt b/online-inference/custom-sentiment/custom-predictor/requirements.txt
index 1302b990..40c1c369 100644
--- a/online-inference/custom-sentiment/custom-predictor/requirements.txt
+++ b/online-inference/custom-sentiment/custom-predictor/requirements.txt
@@ -1,3 +1,4 @@
 kfserving==0.5.1
 fastai==1.0.61
 torch==1.5.0
+tornado>=6.4.2 # not directly required, pinned by Snyk to avoid a vulnerability