diff --git a/test-requirements.txt b/test-requirements.txt
index 3858915..89407b9 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -1,3 +1,4 @@
 pytest>=2.7.2
 pylint>=1.7.1
 pytest-cov>=2.9
+zipp>=3.19.1 # not directly required, pinned by Snyk to avoid a vulnerability