diff --git a/requirements.txt b/requirements.txt
index e87080e..29bd68f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -17,3 +17,4 @@ accessstatsapi==1.2.0
 publicationstatsapi==1.2.0
 articlemetaapi==1.14.19
 altmetric==1.0.0
+idna>=3.7 # not directly required, pinned by Snyk to avoid a vulnerability