--- a/plugins/muc/muc.lib.lua	Fri Mar 09 19:03:50 2018 +0100
+++ b/plugins/muc/muc.lib.lua	Mon Jun 18 04:25:01 2018 +0200
@@ -51,6 +51,7 @@
 		affiliation = affiliation;
 		affiliation_rank = valid_affiliations[affiliation or "none"];
 	});
+	role = role ~= "none" and role or nil; -- coerces `role == false` to `nil`
 	return role, valid_roles[role or "none"];
 end
 module:hook("muc-get-default-role", function(event)