diff --git a/letsencrypt/cli.py b/letsencrypt/cli.py
index b8a17d70e..d997cb3a5 100644
--- a/letsencrypt/cli.py
+++ b/letsencrypt/cli.py
@@ -99,6 +99,10 @@ def usage_strings(plugins):
     return USAGE % (apache_doc, nginx_doc), SHORT_USAGE
 
 
+class _Default(object):
+    """Trivial class used to detect if an option was set by the user."""
+
+
 def set_by_cli(var):
     """
     Return True if a particular config variable has been set by the user