diff --git a/lib/jutil.js b/lib/jutil.js
index 68b0637b..c50e1f22 100644
--- a/lib/jutil.js
+++ b/lib/jutil.js
@@ -66,7 +66,7 @@ exports.mixin = function (newClass, mixinClass, options) {
 };
 
 function mixInto(sourceScope, targetScope, options) {
-  Object.keys(sourceScope).forEach(function (propertyName, options) {
+  Object.keys(sourceScope).forEach(function (propertyName) {
     var targetPropertyExists = targetScope.hasOwnProperty(propertyName);
     var sourceProperty = Object.getOwnPropertyDescriptor(sourceScope, propertyName);
     var targetProperty = targetPropertyExists && Object.getOwnPropertyDescriptor(targetScope, propertyName);