diff --git a/lib/6to5/transformation/transformers/optional-typeof-symbol.js b/lib/6to5/transformation/transformers/optional-typeof-symbol.js
index 33f803e43f..55be121b08 100644
--- a/lib/6to5/transformation/transformers/optional-typeof-symbol.js
+++ b/lib/6to5/transformation/transformers/optional-typeof-symbol.js
@@ -2,7 +2,7 @@ var t = require("../../types");
 
 exports.optional = true;
 
-exports.UnaryExpression = function (node, parent, file, scope) {
+exports.UnaryExpression = function (node, parent, file) {
   if (node.operator === "typeof") {
     return t.callExpression(file.addHelper("typeof"), [node.argument]);
   }