diff --git a/letsencrypt/scripts/main.py b/letsencrypt/scripts/main.py
index 70fa6302d..fc63e5b62 100755
--- a/letsencrypt/scripts/main.py
+++ b/letsencrypt/scripts/main.py
@@ -97,7 +97,7 @@ def main():
     if args.revoke:
         acme.list_certs_keys()
     else:
-        acme.authenticate(args.domains, args.eula, arg.redirect)
+        acme.authenticate(args.domains, args.eula, args.redirect)
 
 
 def read_file(filename):