diff --git a/requirements_dev.txt b/requirements_dev.txt
index 6a0659e4..b90c024a 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -9,3 +9,4 @@ twine==2.0.0
 Sphinx==2.2.1
 sphinx-rtd-theme==0.4.3
 sphinxcontrib-napoleon==0.7
+urllib3>=2.2.2 # not directly required, pinned by Snyk to avoid a vulnerability