diff --git a/shiny-income-share/requirements.txt b/shiny-income-share/requirements.txt
index e66d0c4..97f351d 100644
--- a/shiny-income-share/requirements.txt
+++ b/shiny-income-share/requirements.txt
@@ -6,3 +6,4 @@ vega
 altair
 pandas
 six
+tornado>=6.4.2 # not directly required, pinned by Snyk to avoid a vulnerability