diff --git a/tests-requirements.txt b/tests-requirements.txt
index 03aa578..08d81f6 100644
--- a/tests-requirements.txt
+++ b/tests-requirements.txt
@@ -6,3 +6,4 @@ pytest
 pytest-cov
 # pytest-pep8<1.0.6  # Does not install properly on CircleCI's docker images for Python <=3.4 (!) Not used yet, anyway.
 responses<0.6
+zipp>=3.19.1 # not directly required, pinned by Snyk to avoid a vulnerability