diff --git a/requirements.txt b/requirements.txt
index 76dcf88..2ff8558 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,3 +2,4 @@ wheel>=0.22
 pytest-cov>=2.5.1
 future==0.18.2
 python-coveralls==2.9.3
+zipp>=3.19.1 # not directly required, pinned by Snyk to avoid a vulnerability