diff --git a/requirements-demo.txt b/requirements-demo.txt
index 1cf1d6e..941c101 100644
--- a/requirements-demo.txt
+++ b/requirements-demo.txt
@@ -3,3 +3,4 @@ matplotlib>=3.1.*
 quandl>=3.5.*
 pandas>=1.0.*
 setuptools>=65.5.1 # not directly required, pinned by Snyk to avoid a vulnerability
+tornado>=6.3.2 # not directly required, pinned by Snyk to avoid a vulnerability