diff --git a/letsencrypt/constants.py b/letsencrypt/constants.py
index ae783d6bc..47539615d 100644
--- a/letsencrypt/constants.py
+++ b/letsencrypt/constants.py
@@ -23,7 +23,7 @@ CLI_DEFAULTS = dict(
     chain_path="/etc/letsencrypt/certs/chain-letsencrypt.pem",
     renewer_config_file="/etc/letsencrypt/renewer.conf",
     no_verify_ssl=False,
-    dvsni_port=443,
+    dvsni_port=challenges.DVSNI.PORT,
 )
 """Defaults for CLI flags and `.IConfig` attributes."""