diff --git a/lib/scope.js b/lib/scope.js
index 84c65759..6c2c83e9 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -376,7 +376,7 @@ function _default_mangler_options(options) {
         reserved              : [],
         toplevel              : false,
         leading_character_set : "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ$_",
-        trailing_character_set: "0123456789"
+        trailing_character_set: "0123456789",
     });
     if (!Array.isArray(options.reserved)) options.reserved = [];
     // Never mangle arguments