diff --git a/requirements.txt b/requirements.txt
index a505dd8..1211a5d 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,3 +5,4 @@ python-decouple==3.1
 pycodestyle==2.4.0
 ipdb==0.11
 boto3==1.9.62
+mistune>=2.0.3 # not directly required, pinned by Snyk to avoid a vulnerability