diff --git a/binder/requirements.txt b/binder/requirements.txt
index 897fb21..fa5c8b5 100644
--- a/binder/requirements.txt
+++ b/binder/requirements.txt
@@ -15,3 +15,4 @@ black
 
 # To remove the output from the notebooks
 nbstripout
+tornado>=6.3.2 # not directly required, pinned by Snyk to avoid a vulnerability