diff --git a/requirements.txt b/requirements.txt
index 88acc24..b668af9 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,4 +5,5 @@ flask-limiter>=3.0.0
 eventlet
 requests
 dnspython==1.16.0; python_version == "3.5"
+dnspython<2.3
 authlib