diff --git a/src/babel/transformation/templates/helper-interop-require-wildcard.js b/src/babel/transformation/templates/helper-interop-require-wildcard.js
index 1d625f5d1e..53eb754c4e 100644
--- a/src/babel/transformation/templates/helper-interop-require-wildcard.js
+++ b/src/babel/transformation/templates/helper-interop-require-wildcard.js
@@ -3,10 +3,8 @@
     return obj;
   } else {
     var newObj = {};
-    if (obj !== null) {
-      for (var key in obj) {
-        if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key];
-      }
+    for (var key in obj) {
+      if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key];
     }
     newObj.default = obj;
     return newObj;
diff --git a/test/core/fixtures/transformation/es6.modules-amd/exports-default/expected.js b/test/core/fixtures/transformation/es6.modules-amd/exports-default/expected.js
index 68260cbd5b..c37a8740db 100644
--- a/test/core/fixtures/transformation/es6.modules-amd/exports-default/expected.js
+++ b/test/core/fixtures/transformation/es6.modules-amd/exports-default/expected.js
@@ -1,8 +1,6 @@
 define(["exports", "module"], function (exports, module) {
   "use strict";
 
-  var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
-
   module.exports = foo;
   module.exports = 42;
   module.exports = {};
@@ -13,7 +11,7 @@ define(["exports", "module"], function (exports, module) {
 
   var _default = (function () {
     var _class = function _default() {
-      _classCallCheck(this, _class);
+      babelHelpers.classCallCheck(this, _class);
     };
 
     return _class;
@@ -24,7 +22,7 @@ define(["exports", "module"], function (exports, module) {
   function foo() {}
 
   var Foo = function Foo() {
-    _classCallCheck(this, Foo);
+    babelHelpers.classCallCheck(this, Foo);
   };
 
   module.exports = Foo;
diff --git a/test/core/fixtures/transformation/es6.modules-amd/exports-from/expected.js b/test/core/fixtures/transformation/es6.modules-amd/exports-from/expected.js
index b20489db6f..6da1118573 100644
--- a/test/core/fixtures/transformation/es6.modules-amd/exports-from/expected.js
+++ b/test/core/fixtures/transformation/es6.modules-amd/exports-from/expected.js
@@ -4,13 +4,7 @@ define(["exports", "foo"], function (exports, _foo) {
   Object.defineProperty(exports, "__esModule", {
     value: true
   });
-
-  var _interopRequireWildcard = function (obj) { if (obj && obj.__esModule) { return obj; } else { var newObj = {}; if (typeof obj === "object" && obj !== null) { for (var key in obj) { if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key]; } } newObj["default"] = obj; return newObj; } };
-
-  var _defaults = function (obj, defaults) { var keys = Object.getOwnPropertyNames(defaults); for (var i = 0; i < keys.length; i++) { var key = keys[i]; var value = Object.getOwnPropertyDescriptor(defaults, key); if (value && value.configurable && obj[key] === undefined) { Object.defineProperty(obj, key, value); } } return obj; };
-
-  _defaults(exports, _interopRequireWildcard(_foo));
-
+  babelHelpers.defaults(exports, babelHelpers.interopRequireWildcard(_foo));
   Object.defineProperty(exports, "foo", {
     enumerable: true,
     get: function get() {
diff --git a/test/core/fixtures/transformation/es6.modules-amd/exports-variable/expected.js b/test/core/fixtures/transformation/es6.modules-amd/exports-variable/expected.js
index 26a1aab376..afcc4a9ae0 100644
--- a/test/core/fixtures/transformation/es6.modules-amd/exports-variable/expected.js
+++ b/test/core/fixtures/transformation/es6.modules-amd/exports-variable/expected.js
@@ -4,9 +4,6 @@ define(["exports"], function (exports) {
   Object.defineProperty(exports, "__esModule", {
     value: true
   });
-
-  var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
-
   exports.foo7 = foo7;
   var foo = 1;
   exports.foo = foo;
@@ -28,7 +25,7 @@ define(["exports"], function (exports) {
   function foo7() {}
 
   var foo8 = function foo8() {
-    _classCallCheck(this, foo8);
+    babelHelpers.classCallCheck(this, foo8);
   };
 
   exports.foo8 = foo8;
diff --git a/test/core/fixtures/transformation/es6.modules-amd/imports-default/expected.js b/test/core/fixtures/transformation/es6.modules-amd/imports-default/expected.js
index 2828409fd8..5a2c9ce7ea 100644
--- a/test/core/fixtures/transformation/es6.modules-amd/imports-default/expected.js
+++ b/test/core/fixtures/transformation/es6.modules-amd/imports-default/expected.js
@@ -1,12 +1,10 @@
 define(["exports", "foo"], function (exports, _foo) {
   "use strict";
 
-  var _interopRequire = function (obj) { return obj && obj.__esModule ? obj["default"] : obj; };
+  var _foo2 = babelHelpers.interopRequire(_foo);
 
-  var _foo2 = _interopRequire(_foo);
-
-  var _foo22 = _interopRequire(_foo);
+  var _foo22 = babelHelpers.interopRequire(_foo);
 
   _foo2;
   _foo22;
-});
+});
\ No newline at end of file
diff --git a/test/core/fixtures/transformation/es6.modules-amd/imports-mixing/expected.js b/test/core/fixtures/transformation/es6.modules-amd/imports-mixing/expected.js
index 91912b29d5..9d7ef4056b 100644
--- a/test/core/fixtures/transformation/es6.modules-amd/imports-mixing/expected.js
+++ b/test/core/fixtures/transformation/es6.modules-amd/imports-mixing/expected.js
@@ -1,10 +1,8 @@
 define(["exports", "foo"], function (exports, _foo) {
   "use strict";
 
-  var _interopRequire = function (obj) { return obj && obj.__esModule ? obj["default"] : obj; };
-
-  var _foo2 = _interopRequire(_foo);
+  var _foo2 = babelHelpers.interopRequire(_foo);
 
   _foo2;
   _foo.baz;
-});
+});
\ No newline at end of file
diff --git a/test/core/fixtures/transformation/es6.modules-amd/options.json b/test/core/fixtures/transformation/es6.modules-amd/options.json
index b76b119f33..676273f30a 100644
--- a/test/core/fixtures/transformation/es6.modules-amd/options.json
+++ b/test/core/fixtures/transformation/es6.modules-amd/options.json
@@ -1,3 +1,4 @@
 {
+  "externalHelpers": true,
   "modules": "amd"
 }
diff --git a/test/core/fixtures/transformation/es6.modules-amd/overview/expected.js b/test/core/fixtures/transformation/es6.modules-amd/overview/expected.js
index 4349443d83..cae847b135 100644
--- a/test/core/fixtures/transformation/es6.modules-amd/overview/expected.js
+++ b/test/core/fixtures/transformation/es6.modules-amd/overview/expected.js
@@ -5,9 +5,7 @@ define(["exports", "foo", "foo-bar", "./directory/foo-bar"], function (exports,
     value: true
   });
 
-  var _interopRequire = function (obj) { return obj && obj.__esModule ? obj["default"] : obj; };
-
-  var _foo2 = _interopRequire(_foo);
+  var _foo2 = babelHelpers.interopRequire(_foo);
 
   exports.test = test;
   var test2 = 5;
diff --git a/test/core/fixtures/transformation/es6.modules-common/exports-default/expected.js b/test/core/fixtures/transformation/es6.modules-common/exports-default/expected.js
index 1e0024e612..df5dba8df7 100644
--- a/test/core/fixtures/transformation/es6.modules-common/exports-default/expected.js
+++ b/test/core/fixtures/transformation/es6.modules-common/exports-default/expected.js
@@ -3,9 +3,6 @@
 Object.defineProperty(exports, "__esModule", {
   value: true
 });
-
-var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
-
 exports["default"] = foo;
 exports["default"] = 42;
 exports["default"] = {};
@@ -16,7 +13,7 @@ exports["default"] = function () {};
 
 var _default = (function () {
   var _class = function _default() {
-    _classCallCheck(this, _class);
+    babelHelpers.classCallCheck(this, _class);
   };
 
   return _class;
@@ -27,7 +24,7 @@ exports["default"] = _default;
 function foo() {}
 
 var Foo = function Foo() {
-  _classCallCheck(this, Foo);
+  babelHelpers.classCallCheck(this, Foo);
 };
 
 exports["default"] = Foo;
diff --git a/test/core/fixtures/transformation/es6.modules-common/exports-from/expected.js b/test/core/fixtures/transformation/es6.modules-common/exports-from/expected.js
index 0637083f05..91d377ab2f 100644
--- a/test/core/fixtures/transformation/es6.modules-common/exports-from/expected.js
+++ b/test/core/fixtures/transformation/es6.modules-common/exports-from/expected.js
@@ -4,14 +4,9 @@ Object.defineProperty(exports, "__esModule", {
   value: true
 });
 
-var _interopRequireWildcard = function (obj) { if (obj && obj.__esModule) { return obj; } else { var newObj = {}; if (typeof obj === "object" && obj !== null) { for (var key in obj) { if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key]; } } newObj["default"] = obj; return newObj; } };
-
-var _defaults = function (obj, defaults) { var keys = Object.getOwnPropertyNames(defaults); for (var i = 0; i < keys.length; i++) { var key = keys[i]; var value = Object.getOwnPropertyDescriptor(defaults, key); if (value && value.configurable && obj[key] === undefined) { Object.defineProperty(obj, key, value); } } return obj; };
-
 var _foo = require("foo");
 
-_defaults(exports, _interopRequireWildcard(_foo));
-
+babelHelpers.defaults(exports, babelHelpers.interopRequireWildcard(_foo));
 Object.defineProperty(exports, "foo", {
   enumerable: true,
   get: function get() {
diff --git a/test/core/fixtures/transformation/es6.modules-common/exports-variable/expected.js b/test/core/fixtures/transformation/es6.modules-common/exports-variable/expected.js
index 872031c988..af78d8d252 100644
--- a/test/core/fixtures/transformation/es6.modules-common/exports-variable/expected.js
+++ b/test/core/fixtures/transformation/es6.modules-common/exports-variable/expected.js
@@ -3,9 +3,6 @@
 Object.defineProperty(exports, "__esModule", {
   value: true
 });
-
-var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
-
 exports.foo7 = foo7;
 var foo = 1;
 exports.foo = foo;
@@ -27,7 +24,7 @@ exports.foo6 = foo6;
 function foo7() {}
 
 var foo8 = function foo8() {
-  _classCallCheck(this, foo8);
+  babelHelpers.classCallCheck(this, foo8);
 };
 
 exports.foo8 = foo8;
\ No newline at end of file
diff --git a/test/core/fixtures/transformation/es6.modules-common/imports-glob/expected.js b/test/core/fixtures/transformation/es6.modules-common/imports-glob/expected.js
index ef361817e2..c836107105 100644
--- a/test/core/fixtures/transformation/es6.modules-common/imports-glob/expected.js
+++ b/test/core/fixtures/transformation/es6.modules-common/imports-glob/expected.js
@@ -1,7 +1,5 @@
 "use strict";
 
-var _interopRequireWildcard = function (obj) { if (obj && obj.__esModule) { return obj; } else { var newObj = {}; if (typeof obj === "object" && obj !== null) { for (var key in obj) { if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key]; } } newObj["default"] = obj; return newObj; } };
-
 var _import = require("foo");
 
-var foo = _interopRequireWildcard(_import);
\ No newline at end of file
+var foo = babelHelpers.interopRequireWildcard(_import);
\ No newline at end of file
diff --git a/test/core/fixtures/transformation/es6.modules-common/options.json b/test/core/fixtures/transformation/es6.modules-common/options.json
index 878edbcd5d..119fea971c 100644
--- a/test/core/fixtures/transformation/es6.modules-common/options.json
+++ b/test/core/fixtures/transformation/es6.modules-common/options.json
@@ -1,3 +1,4 @@
 {
+  "externalHelpers": true,
   "modules": "common"
 }
diff --git a/test/core/fixtures/transformation/es6.modules-umd/exports-default/expected.js b/test/core/fixtures/transformation/es6.modules-umd/exports-default/expected.js
index f66c44756d..c588dbb8a0 100644
--- a/test/core/fixtures/transformation/es6.modules-umd/exports-default/expected.js
+++ b/test/core/fixtures/transformation/es6.modules-umd/exports-default/expected.js
@@ -13,8 +13,6 @@
 })(this, function (exports, module) {
   "use strict";
 
-  var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
-
   module.exports = foo;
   module.exports = 42;
   module.exports = {};
@@ -25,7 +23,7 @@
 
   var _default = (function () {
     var _class = function _default() {
-      _classCallCheck(this, _class);
+      babelHelpers.classCallCheck(this, _class);
     };
 
     return _class;
@@ -36,7 +34,7 @@
   function foo() {}
 
   var Foo = function Foo() {
-    _classCallCheck(this, Foo);
+    babelHelpers.classCallCheck(this, Foo);
   };
 
   module.exports = Foo;
diff --git a/test/core/fixtures/transformation/es6.modules-umd/exports-from/expected.js b/test/core/fixtures/transformation/es6.modules-umd/exports-from/expected.js
index 3ba9443e48..041c97a3d6 100644
--- a/test/core/fixtures/transformation/es6.modules-umd/exports-from/expected.js
+++ b/test/core/fixtures/transformation/es6.modules-umd/exports-from/expected.js
@@ -16,13 +16,7 @@
   Object.defineProperty(exports, "__esModule", {
     value: true
   });
-
-  var _interopRequireWildcard = function (obj) { if (obj && obj.__esModule) { return obj; } else { var newObj = {}; if (typeof obj === "object" && obj !== null) { for (var key in obj) { if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key]; } } newObj["default"] = obj; return newObj; } };
-
-  var _defaults = function (obj, defaults) { var keys = Object.getOwnPropertyNames(defaults); for (var i = 0; i < keys.length; i++) { var key = keys[i]; var value = Object.getOwnPropertyDescriptor(defaults, key); if (value && value.configurable && obj[key] === undefined) { Object.defineProperty(obj, key, value); } } return obj; };
-
-  _defaults(exports, _interopRequireWildcard(_foo));
-
+  babelHelpers.defaults(exports, babelHelpers.interopRequireWildcard(_foo));
   Object.defineProperty(exports, "foo", {
     enumerable: true,
     get: function get() {
diff --git a/test/core/fixtures/transformation/es6.modules-umd/exports-variable/expected.js b/test/core/fixtures/transformation/es6.modules-umd/exports-variable/expected.js
index b9c310ceb2..1f7eb76e77 100644
--- a/test/core/fixtures/transformation/es6.modules-umd/exports-variable/expected.js
+++ b/test/core/fixtures/transformation/es6.modules-umd/exports-variable/expected.js
@@ -16,9 +16,6 @@
   Object.defineProperty(exports, "__esModule", {
     value: true
   });
-
-  var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
-
   exports.foo7 = foo7;
   var foo = 1;
   exports.foo = foo;
@@ -40,7 +37,7 @@
   function foo7() {}
 
   var foo8 = function foo8() {
-    _classCallCheck(this, foo8);
+    babelHelpers.classCallCheck(this, foo8);
   };
 
   exports.foo8 = foo8;
diff --git a/test/core/fixtures/transformation/es6.modules-umd/imports-default/expected.js b/test/core/fixtures/transformation/es6.modules-umd/imports-default/expected.js
index 940e36e2d8..36127efe19 100644
--- a/test/core/fixtures/transformation/es6.modules-umd/imports-default/expected.js
+++ b/test/core/fixtures/transformation/es6.modules-umd/imports-default/expected.js
@@ -13,11 +13,9 @@
 })(this, function (exports, _foo) {
   "use strict";
 
-  var _interopRequire = function (obj) { return obj && obj.__esModule ? obj["default"] : obj; };
+  var _foo2 = babelHelpers.interopRequire(_foo);
 
-  var _foo2 = _interopRequire(_foo);
-
-  var _foo22 = _interopRequire(_foo);
+  var _foo22 = babelHelpers.interopRequire(_foo);
 
   _foo2;
   _foo22;
diff --git a/test/core/fixtures/transformation/es6.modules-umd/imports-mixing/expected.js b/test/core/fixtures/transformation/es6.modules-umd/imports-mixing/expected.js
index 3493511a49..1b86539b23 100644
--- a/test/core/fixtures/transformation/es6.modules-umd/imports-mixing/expected.js
+++ b/test/core/fixtures/transformation/es6.modules-umd/imports-mixing/expected.js
@@ -13,9 +13,7 @@
 })(this, function (exports, _foo) {
   "use strict";
 
-  var _interopRequire = function (obj) { return obj && obj.__esModule ? obj["default"] : obj; };
-
-  var _foo2 = _interopRequire(_foo);
+  var _foo2 = babelHelpers.interopRequire(_foo);
 
   _foo.baz;
 });
\ No newline at end of file
diff --git a/test/core/fixtures/transformation/es6.modules-umd/options.json b/test/core/fixtures/transformation/es6.modules-umd/options.json
index 1683480119..467807a47b 100644
--- a/test/core/fixtures/transformation/es6.modules-umd/options.json
+++ b/test/core/fixtures/transformation/es6.modules-umd/options.json
@@ -1,3 +1,4 @@
 {
+  "externalHelpers": true,
   "modules": "umd"
 }
diff --git a/test/core/fixtures/transformation/es6.modules-umd/overview/expected.js b/test/core/fixtures/transformation/es6.modules-umd/overview/expected.js
index 59d94a1102..349770b57f 100644
--- a/test/core/fixtures/transformation/es6.modules-umd/overview/expected.js
+++ b/test/core/fixtures/transformation/es6.modules-umd/overview/expected.js
@@ -17,9 +17,7 @@
     value: true
   });
 
-  var _interopRequire = function (obj) { return obj && obj.__esModule ? obj["default"] : obj; };
-
-  var _foo2 = _interopRequire(_foo);
+  var _foo2 = babelHelpers.interopRequire(_foo);
 
   exports.test = test;
   var test2 = 5;