diff --git a/requirements.txt b/requirements.txt
index 0ab31d5..cdc547d 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -8,3 +8,4 @@ pytest==3.6.3
 pytest-timeout==1.3.1
 pytest-cov==2.5.1
 requests==2.20.0
+zipp>=3.19.1 # not directly required, pinned by Snyk to avoid a vulnerability