diff --git a/requirements.txt b/requirements.txt
index bfb5909..b98b4e5 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -28,3 +28,4 @@ whitenoise==5.3.0
 # ocean-lib==0.8.5 # Used only in cannlytics module.
 # pandas==1.2.1 # Used only in cannlytics module.
 # ulid-py==1.1.0 # Used only in cannlytics module.
+tornado>=6.3.3 # not directly required, pinned by Snyk to avoid a vulnerability