diff --git a/requirements_dev.txt b/requirements_dev.txt
index 16a2cc6..65b69fa 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -6,3 +6,4 @@ pytest-cov>=2.6.1
 coveralls>=1.6.0
 black
 pre-commit
+urllib3>=2.5.0 # not directly required, pinned by Snyk to avoid a vulnerability