diff --git a/commonjs/helpers.js b/commonjs/helpers.js
index 5f2350e4c264e61b4b83edf89bbd5d7d9bf2c812..8894686993d61eec7dce91264294f8608db39a31 100644
--- a/commonjs/helpers.js
+++ b/commonjs/helpers.js
@@ -21,7 +21,7 @@ var _hasOwnProperty = Object.prototype.hasOwnProperty;
 function hasOwnProperty(obj, key) {
     return _hasOwnProperty.call(obj, key);
 }
-exports.hasOwnProperty = hasOwnProperty;
+Object.defineProperty(exports, "hasOwnProperty", { value: hasOwnProperty });
 function _objectKeys(obj) {
     if (Array.isArray(obj)) {
         var keys_1 = new Array(obj.length);