diff --git a/requirements_dev.txt b/requirements_dev.txt
index ccd0b1b..d86a582 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -7,3 +7,4 @@ pytest-watch==4.2.0
 pytest-bdd==4.0.1
 
 dataclasses==0.8; python_version < "3.7"
+mako>=1.2.2 # not directly required, pinned by Snyk to avoid a vulnerability