diff --git a/lib/6to5/file.js b/lib/6to5/file.js
index cbb26b5218..f0e6da985b 100644
--- a/lib/6to5/file.js
+++ b/lib/6to5/file.js
@@ -51,7 +51,9 @@ File.helpers = [
   "typeof",
   "extends",
   "get",
-  "set"
+  "set",
+  "class-call-check",
+  "class-super-constructor-call"
 ];
 
 File.validOptions = [
diff --git a/lib/6to5/transformation/templates/class-call-check.js b/lib/6to5/transformation/templates/class-call-check.js
new file mode 100644
index 0000000000..041dd4b753
--- /dev/null
+++ b/lib/6to5/transformation/templates/class-call-check.js
@@ -0,0 +1,5 @@
+(function (instance, Constructor) {
+  if (!(instance instanceof Constructor)) {
+    throw new TypeError("Cannot call a class as a function");
+  }
+});
diff --git a/lib/6to5/transformation/templates/class-super-constructor-call.js b/lib/6to5/transformation/templates/class-super-constructor-call.js
index 21034b6201..7395389e91 100644
--- a/lib/6to5/transformation/templates/class-super-constructor-call.js
+++ b/lib/6to5/transformation/templates/class-super-constructor-call.js
@@ -1,3 +1,5 @@
-if (Object.getPrototypeOf(CLASS_NAME) !== null) {
-  Object.getPrototypeOf(CLASS_NAME).apply(this, arguments);
-}
+(function (Constructor) {
+  if (Object.getPrototypeOf(Constructor) !== null) {
+    Object.getPrototypeOf(Constructor).apply(this, arguments);
+  }
+});
diff --git a/lib/6to5/transformation/transformers/es6/classes.js b/lib/6to5/transformation/transformers/es6/classes.js
index 1b025d72f6..c320f06064 100644
--- a/lib/6to5/transformation/transformers/es6/classes.js
+++ b/lib/6to5/transformation/transformers/es6/classes.js
@@ -67,12 +67,19 @@ Class.prototype.run = function () {
 
   var body = this.body = [];
 
+  var constructorBody = t.blockStatement([
+    t.expressionStatement(t.callExpression(file.addHelper("class-call-check"), [
+      t.thisExpression(),
+      className
+    ]))
+  ]);
   var constructor;
+
   if (this.node.id) {
-    constructor = t.functionDeclaration(className, [], t.blockStatement([]));
+    constructor = t.functionDeclaration(className, [], constructorBody);
     body.push(constructor);
   } else {
-    constructor = t.functionExpression(null, [], t.blockStatement([]));
+    constructor = t.functionExpression(null, [], constructorBody);
     body.push(t.variableDeclaration("var", [
       t.variableDeclarator(className, constructor)
     ]));
@@ -161,13 +168,18 @@ Class.prototype.buildBody = function () {
 
   // we have no constructor, we have a super, and the super doesn't appear to be falsy
   if (!this.hasConstructor && superName && !t.isFalsyExpression(superName)) {
-    var defaultConstructorTemplate = "class-super-constructor-call";
-    if (this.isLoose) defaultConstructorTemplate += "-loose";
+    var helperName = "class-super-constructor-call";
 
-    constructor.body.body.push(util.template(defaultConstructorTemplate, {
-      CLASS_NAME: className,
-      SUPER_NAME: this.superName
-    }, true));
+    if (this.isLoose) {
+      constructor.body.body.push(util.template(helperName + "-loose", {
+        CLASS_NAME: className,
+        SUPER_NAME: this.superName
+      }, true));
+    } else {
+      constructor.body.body.push(
+        t.expressionStatement(t.callExpression(this.file.addHelper(helperName), [className]))
+      );
+    }
   }
 
   var instanceProps;
@@ -256,5 +268,5 @@ Class.prototype.pushConstructor = function (method) {
 
   construct._ignoreUserWhitespace = true;
   construct.params                = fn.params;
-  construct.body                  = fn.body;
+  construct.body.body             = construct.body.body.concat(fn.body.body);
 };
diff --git a/test/fixtures/transformation/api/blacklist/expected.js b/test/fixtures/transformation/api/blacklist/expected.js
index 01fd9509ac..934fea14ff 100644
--- a/test/fixtures/transformation/api/blacklist/expected.js
+++ b/test/fixtures/transformation/api/blacklist/expected.js
@@ -1,5 +1,9 @@
 "use strict";
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Test = function Test() {
+  _classCallCheck(this, Test);
+
   arr.map(x => x * x);
-};
+};
\ No newline at end of file
diff --git a/test/fixtures/transformation/async-to-generator/async/expected.js b/test/fixtures/transformation/async-to-generator/async/expected.js
index 7a1578f1ca..ff97e4796e 100644
--- a/test/fixtures/transformation/async-to-generator/async/expected.js
+++ b/test/fixtures/transformation/async-to-generator/async/expected.js
@@ -4,8 +4,12 @@ var _asyncToGenerator = function (fn) { return function () { var gen = fn.apply(
 
 var _prototypeProperties = function (child, staticProps, instanceProps) { if (staticProps) Object.defineProperties(child, staticProps); if (instanceProps) Object.defineProperties(child.prototype, instanceProps); };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Foo = (function () {
-  function Foo() {}
+  function Foo() {
+    _classCallCheck(this, Foo);
+  }
 
   _prototypeProperties(Foo, null, {
     foo: {
diff --git a/test/fixtures/transformation/bluebird-coroutines/class/expected.js b/test/fixtures/transformation/bluebird-coroutines/class/expected.js
index 9217530fdc..fdb5965add 100644
--- a/test/fixtures/transformation/bluebird-coroutines/class/expected.js
+++ b/test/fixtures/transformation/bluebird-coroutines/class/expected.js
@@ -4,8 +4,12 @@ var _bluebird = require("bluebird");
 
 var _prototypeProperties = function (child, staticProps, instanceProps) { if (staticProps) Object.defineProperties(child, staticProps); if (instanceProps) Object.defineProperties(child.prototype, instanceProps); };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Foo = (function () {
-  function Foo() {}
+  function Foo() {
+    _classCallCheck(this, Foo);
+  }
 
   _prototypeProperties(Foo, null, {
     foo: {
diff --git a/test/fixtures/transformation/es6-classes-loose/accessing-super-class/expected.js b/test/fixtures/transformation/es6-classes-loose/accessing-super-class/expected.js
index 1aee2c69ea..0af6c4445f 100644
--- a/test/fixtures/transformation/es6-classes-loose/accessing-super-class/expected.js
+++ b/test/fixtures/transformation/es6-classes-loose/accessing-super-class/expected.js
@@ -3,9 +3,13 @@
 var _slice = Array.prototype.slice;
 var _inherits = function (subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) subClass.__proto__ = superClass; };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Test = (function (Foo) {
   function Test() {
     var _Foo$prototype$test, _Foo$prototype$test2;
+    _classCallCheck(this, Test);
+
     woops["super"].test();
     Foo.call(this);
     Foo.prototype.test.call(this);
diff --git a/test/fixtures/transformation/es6-classes-loose/accessing-super-properties/expected.js b/test/fixtures/transformation/es6-classes-loose/accessing-super-properties/expected.js
index 9847c19e45..915798aa48 100644
--- a/test/fixtures/transformation/es6-classes-loose/accessing-super-properties/expected.js
+++ b/test/fixtures/transformation/es6-classes-loose/accessing-super-properties/expected.js
@@ -2,8 +2,12 @@
 
 var _inherits = function (subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) subClass.__proto__ = superClass; };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Test = (function (Foo) {
   function Test() {
+    _classCallCheck(this, Test);
+
     Foo.prototype.test;
     Foo.prototype.test.whatever;
   }
diff --git a/test/fixtures/transformation/es6-classes-loose/calling-super-properties/expected.js b/test/fixtures/transformation/es6-classes-loose/calling-super-properties/expected.js
index 4caab68366..8b66f1fafe 100644
--- a/test/fixtures/transformation/es6-classes-loose/calling-super-properties/expected.js
+++ b/test/fixtures/transformation/es6-classes-loose/calling-super-properties/expected.js
@@ -2,8 +2,12 @@
 
 var _inherits = function (subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) subClass.__proto__ = superClass; };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Test = (function (Foo) {
   function Test() {
+    _classCallCheck(this, Test);
+
     Foo.prototype.test.whatever();
     Foo.prototype.test.call(this);
   }
diff --git a/test/fixtures/transformation/es6-classes-loose/super-class-id-member-expression/expected.js b/test/fixtures/transformation/es6-classes-loose/super-class-id-member-expression/expected.js
index 708616d6a9..e277b544fd 100644
--- a/test/fixtures/transformation/es6-classes-loose/super-class-id-member-expression/expected.js
+++ b/test/fixtures/transformation/es6-classes-loose/super-class-id-member-expression/expected.js
@@ -2,8 +2,12 @@
 
 var _inherits = function (subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) subClass.__proto__ = superClass; };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var BaseController = (function (_Chaplin$Controller) {
   function BaseController() {
+    _classCallCheck(this, BaseController);
+
     if (_Chaplin$Controller != null) {
       _Chaplin$Controller.apply(this, arguments);
     }
@@ -16,6 +20,8 @@ var BaseController = (function (_Chaplin$Controller) {
 
 var BaseController2 = (function (_Chaplin$Controller$Another) {
   function BaseController2() {
+    _classCallCheck(this, BaseController2);
+
     if (_Chaplin$Controller$Another != null) {
       _Chaplin$Controller$Another.apply(this, arguments);
     }
diff --git a/test/fixtures/transformation/es6-classes-loose/super-class/expected.js b/test/fixtures/transformation/es6-classes-loose/super-class/expected.js
index b57997b371..338d66b696 100644
--- a/test/fixtures/transformation/es6-classes-loose/super-class/expected.js
+++ b/test/fixtures/transformation/es6-classes-loose/super-class/expected.js
@@ -2,8 +2,12 @@
 
 var _inherits = function (subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) subClass.__proto__ = superClass; };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Test = (function (Foo) {
   function Test() {
+    _classCallCheck(this, Test);
+
     if (Foo != null) {
       Foo.apply(this, arguments);
     }
diff --git a/test/fixtures/transformation/es6-classes-loose/super-function-fallback/expected.js b/test/fixtures/transformation/es6-classes-loose/super-function-fallback/expected.js
index e17e74db06..8f393151d3 100644
--- a/test/fixtures/transformation/es6-classes-loose/super-function-fallback/expected.js
+++ b/test/fixtures/transformation/es6-classes-loose/super-function-fallback/expected.js
@@ -1,5 +1,9 @@
 "use strict";
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Test = function Test() {
+  _classCallCheck(this, Test);
+
   Function.prototype.hasOwnProperty.call(this, "test");
-};
+};
\ No newline at end of file
diff --git a/test/fixtures/transformation/es6-classes/accessing-super-class/expected.js b/test/fixtures/transformation/es6-classes/accessing-super-class/expected.js
index 264c6a4146..a8f74b0cb7 100644
--- a/test/fixtures/transformation/es6-classes/accessing-super-class/expected.js
+++ b/test/fixtures/transformation/es6-classes/accessing-super-class/expected.js
@@ -7,9 +7,13 @@ var _get = function get(object, property, receiver) { var desc = Object.getOwnPr
 
 var _inherits = function (subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) subClass.__proto__ = superClass; };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Test = (function (Foo) {
   function Test() {
     var _get2, _get3;
+    _classCallCheck(this, Test);
+
     woops["super"].test();
     _get(Object.getPrototypeOf(Test.prototype), "constructor", this).call(this);
     _get(Object.getPrototypeOf(Test.prototype), "test", this).call(this);
diff --git a/test/fixtures/transformation/es6-classes/accessing-super-properties/expected.js b/test/fixtures/transformation/es6-classes/accessing-super-properties/expected.js
index 037d172454..7ee14a53f1 100644
--- a/test/fixtures/transformation/es6-classes/accessing-super-properties/expected.js
+++ b/test/fixtures/transformation/es6-classes/accessing-super-properties/expected.js
@@ -4,8 +4,12 @@ var _get = function get(object, property, receiver) { var desc = Object.getOwnPr
 
 var _inherits = function (subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) subClass.__proto__ = superClass; };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Test = (function (Foo) {
   function Test() {
+    _classCallCheck(this, Test);
+
     _get(Object.getPrototypeOf(Test.prototype), "test", this);
     _get(Object.getPrototypeOf(Test.prototype), "test", this).whatever;
   }
diff --git a/test/fixtures/transformation/es6-classes/calling-super-properties/expected.js b/test/fixtures/transformation/es6-classes/calling-super-properties/expected.js
index b83d270ae3..4ae369971d 100644
--- a/test/fixtures/transformation/es6-classes/calling-super-properties/expected.js
+++ b/test/fixtures/transformation/es6-classes/calling-super-properties/expected.js
@@ -6,8 +6,12 @@ var _get = function get(object, property, receiver) { var desc = Object.getOwnPr
 
 var _inherits = function (subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) subClass.__proto__ = superClass; };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Test = (function (Foo) {
   function Test() {
+    _classCallCheck(this, Test);
+
     _get(Object.getPrototypeOf(Test.prototype), "test", this).whatever();
     _get(Object.getPrototypeOf(Test.prototype), "test", this).call(this);
   }
diff --git a/test/fixtures/transformation/es6-classes/constructor/expected.js b/test/fixtures/transformation/es6-classes/constructor/expected.js
index 6750599c80..69e8c55d3b 100644
--- a/test/fixtures/transformation/es6-classes/constructor/expected.js
+++ b/test/fixtures/transformation/es6-classes/constructor/expected.js
@@ -2,12 +2,18 @@
 
 var _inherits = function (subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) subClass.__proto__ = superClass; };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Test = function Test() {
+  _classCallCheck(this, Test);
+
   this.state = "test";
 };
 
 var Foo = (function (Bar) {
   function Foo() {
+    _classCallCheck(this, Foo);
+
     this.state = "test";
   }
 
diff --git a/test/fixtures/transformation/es6-classes/instance-getter-and-setter/expected.js b/test/fixtures/transformation/es6-classes/instance-getter-and-setter/expected.js
index 031271c3b8..f4bb836401 100644
--- a/test/fixtures/transformation/es6-classes/instance-getter-and-setter/expected.js
+++ b/test/fixtures/transformation/es6-classes/instance-getter-and-setter/expected.js
@@ -2,8 +2,12 @@
 
 var _prototypeProperties = function (child, staticProps, instanceProps) { if (staticProps) Object.defineProperties(child, staticProps); if (instanceProps) Object.defineProperties(child.prototype, instanceProps); };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Test = (function () {
-  function Test() {}
+  function Test() {
+    _classCallCheck(this, Test);
+  }
 
   _prototypeProperties(Test, null, {
     test: {
diff --git a/test/fixtures/transformation/es6-classes/instance-getter/expected.js b/test/fixtures/transformation/es6-classes/instance-getter/expected.js
index 2dc7c8a867..17f3dc1e1a 100644
--- a/test/fixtures/transformation/es6-classes/instance-getter/expected.js
+++ b/test/fixtures/transformation/es6-classes/instance-getter/expected.js
@@ -2,8 +2,12 @@
 
 var _prototypeProperties = function (child, staticProps, instanceProps) { if (staticProps) Object.defineProperties(child, staticProps); if (instanceProps) Object.defineProperties(child.prototype, instanceProps); };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Test = (function () {
-  function Test() {}
+  function Test() {
+    _classCallCheck(this, Test);
+  }
 
   _prototypeProperties(Test, null, {
     test: {
diff --git a/test/fixtures/transformation/es6-classes/instance-method/expected.js b/test/fixtures/transformation/es6-classes/instance-method/expected.js
index 141bd252f7..ff77c0006c 100644
--- a/test/fixtures/transformation/es6-classes/instance-method/expected.js
+++ b/test/fixtures/transformation/es6-classes/instance-method/expected.js
@@ -2,8 +2,12 @@
 
 var _prototypeProperties = function (child, staticProps, instanceProps) { if (staticProps) Object.defineProperties(child, staticProps); if (instanceProps) Object.defineProperties(child.prototype, instanceProps); };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Test = (function () {
-  function Test() {}
+  function Test() {
+    _classCallCheck(this, Test);
+  }
 
   _prototypeProperties(Test, null, {
     test: {
diff --git a/test/fixtures/transformation/es6-classes/instance-setter/expected.js b/test/fixtures/transformation/es6-classes/instance-setter/expected.js
index b45f7b9668..6bd83dcef7 100644
--- a/test/fixtures/transformation/es6-classes/instance-setter/expected.js
+++ b/test/fixtures/transformation/es6-classes/instance-setter/expected.js
@@ -2,8 +2,12 @@
 
 var _prototypeProperties = function (child, staticProps, instanceProps) { if (staticProps) Object.defineProperties(child, staticProps); if (instanceProps) Object.defineProperties(child.prototype, instanceProps); };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Test = (function () {
-  function Test() {}
+  function Test() {
+    _classCallCheck(this, Test);
+  }
 
   _prototypeProperties(Test, null, {
     test: {
diff --git a/test/fixtures/transformation/es6-classes/plain-class/expected.js b/test/fixtures/transformation/es6-classes/plain-class/expected.js
index 5f98760f68..ab3583fca2 100644
--- a/test/fixtures/transformation/es6-classes/plain-class/expected.js
+++ b/test/fixtures/transformation/es6-classes/plain-class/expected.js
@@ -1,3 +1,7 @@
 "use strict";
 
-var Test = function Test() {};
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
+var Test = function Test() {
+  _classCallCheck(this, Test);
+};
\ No newline at end of file
diff --git a/test/fixtures/transformation/es6-classes/statement/expected.js b/test/fixtures/transformation/es6-classes/statement/expected.js
index a54f9ae84a..fb8ea66a32 100644
--- a/test/fixtures/transformation/es6-classes/statement/expected.js
+++ b/test/fixtures/transformation/es6-classes/statement/expected.js
@@ -2,16 +2,24 @@
 
 var _prototypeProperties = function (child, staticProps, instanceProps) { if (staticProps) Object.defineProperties(child, staticProps); if (instanceProps) Object.defineProperties(child.prototype, instanceProps); };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var BaseView = function BaseView() {
+  _classCallCheck(this, BaseView);
+
   this.autoRender = true;
 };
 
 var BaseView = function BaseView() {
+  _classCallCheck(this, BaseView);
+
   this.autoRender = true;
 };
 
 var BaseView = (function () {
-  function BaseView() {}
+  function BaseView() {
+    _classCallCheck(this, BaseView);
+  }
 
   _prototypeProperties(BaseView, null, {
     foo: {
diff --git a/test/fixtures/transformation/es6-classes/static/expected.js b/test/fixtures/transformation/es6-classes/static/expected.js
index 08f1142ffa..0eb86b84bf 100644
--- a/test/fixtures/transformation/es6-classes/static/expected.js
+++ b/test/fixtures/transformation/es6-classes/static/expected.js
@@ -2,8 +2,12 @@
 
 var _prototypeProperties = function (child, staticProps, instanceProps) { if (staticProps) Object.defineProperties(child, staticProps); if (instanceProps) Object.defineProperties(child.prototype, instanceProps); };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var A = (function () {
-  function A() {}
+  function A() {
+    _classCallCheck(this, A);
+  }
 
   _prototypeProperties(A, {
     a: {
diff --git a/test/fixtures/transformation/es6-classes/super-class-id-member-expression/expected.js b/test/fixtures/transformation/es6-classes/super-class-id-member-expression/expected.js
index 9ec5c36b3c..1adf5661ac 100644
--- a/test/fixtures/transformation/es6-classes/super-class-id-member-expression/expected.js
+++ b/test/fixtures/transformation/es6-classes/super-class-id-member-expression/expected.js
@@ -1,12 +1,16 @@
 "use strict";
 
+var _classSuperConstructorCall = function (Constructor) { if (Object.getPrototypeOf(Constructor) !== null) { Object.getPrototypeOf(Constructor).apply(this, arguments); } };
+
 var _inherits = function (subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) subClass.__proto__ = superClass; };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var BaseController = (function (_Chaplin$Controller) {
   function BaseController() {
-    if (Object.getPrototypeOf(BaseController) !== null) {
-      Object.getPrototypeOf(BaseController).apply(this, arguments);
-    }
+    _classCallCheck(this, BaseController);
+
+    _classSuperConstructorCall(BaseController);
   }
 
   _inherits(BaseController, _Chaplin$Controller);
@@ -16,9 +20,9 @@ var BaseController = (function (_Chaplin$Controller) {
 
 var BaseController2 = (function (_Chaplin$Controller$Another) {
   function BaseController2() {
-    if (Object.getPrototypeOf(BaseController2) !== null) {
-      Object.getPrototypeOf(BaseController2).apply(this, arguments);
-    }
+    _classCallCheck(this, BaseController2);
+
+    _classSuperConstructorCall(BaseController2);
   }
 
   _inherits(BaseController2, _Chaplin$Controller$Another);
diff --git a/test/fixtures/transformation/es6-classes/super-class/expected.js b/test/fixtures/transformation/es6-classes/super-class/expected.js
index 845d1c9f91..ab0dc10d23 100644
--- a/test/fixtures/transformation/es6-classes/super-class/expected.js
+++ b/test/fixtures/transformation/es6-classes/super-class/expected.js
@@ -1,12 +1,16 @@
 "use strict";
 
+var _classSuperConstructorCall = function (Constructor) { if (Object.getPrototypeOf(Constructor) !== null) { Object.getPrototypeOf(Constructor).apply(this, arguments); } };
+
 var _inherits = function (subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) subClass.__proto__ = superClass; };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Test = (function (Foo) {
   function Test() {
-    if (Object.getPrototypeOf(Test) !== null) {
-      Object.getPrototypeOf(Test).apply(this, arguments);
-    }
+    _classCallCheck(this, Test);
+
+    _classSuperConstructorCall(Test);
   }
 
   _inherits(Test, Foo);
diff --git a/test/fixtures/transformation/es6-classes/super-function-fallback/expected.js b/test/fixtures/transformation/es6-classes/super-function-fallback/expected.js
index 09fb4b2cea..e278a09b33 100644
--- a/test/fixtures/transformation/es6-classes/super-function-fallback/expected.js
+++ b/test/fixtures/transformation/es6-classes/super-function-fallback/expected.js
@@ -2,6 +2,10 @@
 
 var _get = function get(object, property, receiver) { var desc = Object.getOwnPropertyDescriptor(object, property); if (desc === undefined) { var parent = Object.getPrototypeOf(object); if (parent === null) { return undefined; } else { return get(parent, property, receiver); } } else if ("value" in desc && desc.writable) { return desc.value; } else { var getter = desc.get; if (getter === undefined) { return undefined; } return getter.call(receiver); } };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Test = function Test() {
+  _classCallCheck(this, Test);
+
   _get(Object.getPrototypeOf(Test.prototype), "hasOwnProperty", this).call(this, "test");
 };
\ No newline at end of file
diff --git a/test/fixtures/transformation/es6-modules-amd/exports-default/expected.js b/test/fixtures/transformation/es6-modules-amd/exports-default/expected.js
index 502245b6a1..f67a1d2731 100644
--- a/test/fixtures/transformation/es6-modules-amd/exports-default/expected.js
+++ b/test/fixtures/transformation/es6-modules-amd/exports-default/expected.js
@@ -1,6 +1,8 @@
 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 = {};
@@ -8,11 +10,15 @@ define(["exports", "module"], function (exports, module) {
   module.exports = foo;
   module.exports = function () {};
 
-  var _default = function _default() {};
+  var _default = function _default() {
+    _classCallCheck(this, _default);
+  };
 
   module.exports = _default;
   function foo() {}
-  var Foo = function Foo() {};
+  var Foo = function Foo() {
+    _classCallCheck(this, Foo);
+  };
 
   module.exports = Foo;
 });
\ No newline at end of file
diff --git a/test/fixtures/transformation/es6-modules-amd/exports-variable/expected.js b/test/fixtures/transformation/es6-modules-amd/exports-variable/expected.js
index e8d155830e..156c8b1bac 100644
--- a/test/fixtures/transformation/es6-modules-amd/exports-variable/expected.js
+++ b/test/fixtures/transformation/es6-modules-amd/exports-variable/expected.js
@@ -1,6 +1,8 @@
 define(["exports"], function (exports) {
   "use strict";
 
+  var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
   exports.foo7 = foo7;
   var foo = exports.foo = 1;
   var foo = exports.foo = 1;
@@ -11,7 +13,9 @@ define(["exports"], function (exports) {
   var foo5 = exports.foo5 = undefined;
   var foo6 = exports.foo6 = 3;
   function foo7() {}
-  var foo8 = exports.foo8 = function foo8() {};
+  var foo8 = exports.foo8 = function foo8() {
+    _classCallCheck(this, foo8);
+  };
 
   exports.__esModule = true;
-});
+});
\ No newline at end of file
diff --git a/test/fixtures/transformation/es6-modules-common/exports-default/expected.js b/test/fixtures/transformation/es6-modules-common/exports-default/expected.js
index d5c084b553..f23a52e713 100644
--- a/test/fixtures/transformation/es6-modules-common/exports-default/expected.js
+++ b/test/fixtures/transformation/es6-modules-common/exports-default/expected.js
@@ -1,5 +1,7 @@
 "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 = {};
@@ -7,10 +9,14 @@ module.exports = [];
 module.exports = foo;
 module.exports = function () {};
 
-var _default = function _default() {};
+var _default = function _default() {
+  _classCallCheck(this, _default);
+};
 
 module.exports = _default;
 function foo() {}
-var Foo = function Foo() {};
+var Foo = function Foo() {
+  _classCallCheck(this, Foo);
+};
 
 module.exports = Foo;
\ No newline at end of file
diff --git a/test/fixtures/transformation/es6-modules-common/exports-variable/expected.js b/test/fixtures/transformation/es6-modules-common/exports-variable/expected.js
index 4a196a3ffe..446d62e7e6 100644
--- a/test/fixtures/transformation/es6-modules-common/exports-variable/expected.js
+++ b/test/fixtures/transformation/es6-modules-common/exports-variable/expected.js
@@ -1,5 +1,7 @@
 "use strict";
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 exports.foo7 = foo7;
 var foo = exports.foo = 1;
 var foo = exports.foo = 1;
@@ -10,6 +12,8 @@ var foo4 = exports.foo4 = 2;
 var foo5 = exports.foo5 = undefined;
 var foo6 = exports.foo6 = 3;
 function foo7() {}
-var foo8 = exports.foo8 = function foo8() {};
+var foo8 = exports.foo8 = function foo8() {
+  _classCallCheck(this, foo8);
+};
 
-exports.__esModule = true;
+exports.__esModule = true;
\ No newline at end of file
diff --git a/test/fixtures/transformation/es6-modules-ignore/exports-default/expected.js b/test/fixtures/transformation/es6-modules-ignore/exports-default/expected.js
index 2484b584b3..ea2cae4338 100644
--- a/test/fixtures/transformation/es6-modules-ignore/exports-default/expected.js
+++ b/test/fixtures/transformation/es6-modules-ignore/exports-default/expected.js
@@ -1,6 +1,12 @@
 "use strict";
 
-var _default = function _default() {};
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
+var _default = function _default() {
+  _classCallCheck(this, _default);
+};
 
 function foo() {}
-var Foo = function Foo() {};
\ No newline at end of file
+var Foo = function Foo() {
+  _classCallCheck(this, Foo);
+};
\ No newline at end of file
diff --git a/test/fixtures/transformation/es6-modules-ignore/exports-variable/expected.js b/test/fixtures/transformation/es6-modules-ignore/exports-variable/expected.js
index 11ae89321c..bff6026c5a 100644
--- a/test/fixtures/transformation/es6-modules-ignore/exports-variable/expected.js
+++ b/test/fixtures/transformation/es6-modules-ignore/exports-variable/expected.js
@@ -1,5 +1,7 @@
 "use strict";
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var foo = 1;
 var foo = 1,
     bar = 2;
@@ -9,4 +11,6 @@ var foo4 = 2;
 var foo5 = undefined;
 var foo6 = 3;
 function foo7() {}
-var foo8 = function foo8() {};
+var foo8 = function foo8() {
+  _classCallCheck(this, foo8);
+};
\ No newline at end of file
diff --git a/test/fixtures/transformation/es6-modules-system/exports-default/expected.js b/test/fixtures/transformation/es6-modules-system/exports-default/expected.js
index 88a37c3f83..116c8ce6b6 100644
--- a/test/fixtures/transformation/es6-modules-system/exports-default/expected.js
+++ b/test/fixtures/transformation/es6-modules-system/exports-default/expected.js
@@ -1,13 +1,15 @@
 System.register([], function (_export) {
   "use strict";
 
-  var _default, Foo;
+  var _classCallCheck, _default, Foo;
   _export("default", foo);
 
   function foo() {}
   return {
     setters: [],
     execute: function () {
+      _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
       _export("default", 42);
 
       _export("default", {});
@@ -18,11 +20,15 @@ System.register([], function (_export) {
 
       _export("default", function () {});
 
-      _default = function _default() {};
+      _default = function _default() {
+        _classCallCheck(this, _default);
+      };
 
       _export("default", _default);
 
-      Foo = function Foo() {};
+      Foo = function Foo() {
+        _classCallCheck(this, Foo);
+      };
 
       _export("default", Foo);
     }
diff --git a/test/fixtures/transformation/es6-modules-system/exports-variable/expected.js b/test/fixtures/transformation/es6-modules-system/exports-variable/expected.js
index 740ae60f6c..770cb08145 100644
--- a/test/fixtures/transformation/es6-modules-system/exports-variable/expected.js
+++ b/test/fixtures/transformation/es6-modules-system/exports-variable/expected.js
@@ -1,21 +1,25 @@
 System.register([], function (_export) {
   "use strict";
 
-  var foo, foo2, foo3, foo4, foo5, foo6, foo8;
+  var _classCallCheck, foo, foo2, foo3, foo4, foo5, foo6, foo8;
   _export("foo7", foo7);
 
   function foo7() {}
   return {
     setters: [],
     execute: function () {
+      _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
       foo = _export("foo", 1);
       foo2 = _export("foo2", function () {});
       foo3 = _export("foo3", undefined);
       foo4 = _export("foo4", 2);
       foo5 = _export("foo5", undefined);
       foo6 = _export("foo6", 3);
-      foo8 = _export("foo8", function foo8() {});
+      foo8 = _export("foo8", function foo8() {
+        _classCallCheck(this, foo8);
+      });
       _export("foo3", foo3 = 5);
     }
   };
-});
+});
\ No newline at end of file
diff --git a/test/fixtures/transformation/es6-modules-umd/exports-default/expected.js b/test/fixtures/transformation/es6-modules-umd/exports-default/expected.js
index cd21b0b58b..8470debb5a 100644
--- a/test/fixtures/transformation/es6-modules-umd/exports-default/expected.js
+++ b/test/fixtures/transformation/es6-modules-umd/exports-default/expected.js
@@ -7,6 +7,8 @@
 })(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 = {};
@@ -14,11 +16,15 @@
   module.exports = foo;
   module.exports = function () {};
 
-  var _default = function _default() {};
+  var _default = function _default() {
+    _classCallCheck(this, _default);
+  };
 
   module.exports = _default;
   function foo() {}
-  var Foo = function Foo() {};
+  var Foo = function Foo() {
+    _classCallCheck(this, Foo);
+  };
 
   module.exports = Foo;
 });
\ No newline at end of file
diff --git a/test/fixtures/transformation/es6-modules-umd/exports-variable/expected.js b/test/fixtures/transformation/es6-modules-umd/exports-variable/expected.js
index b5c8cf6185..4857328e4b 100644
--- a/test/fixtures/transformation/es6-modules-umd/exports-variable/expected.js
+++ b/test/fixtures/transformation/es6-modules-umd/exports-variable/expected.js
@@ -7,6 +7,8 @@
 })(function (exports) {
   "use strict";
 
+  var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
   exports.foo7 = foo7;
   var foo = exports.foo = 1;
   var foo = exports.foo = 1;
@@ -17,7 +19,9 @@
   var foo5 = exports.foo5 = undefined;
   var foo6 = exports.foo6 = 3;
   function foo7() {}
-  var foo8 = exports.foo8 = function foo8() {};
+  var foo8 = exports.foo8 = function foo8() {
+    _classCallCheck(this, foo8);
+  };
 
   exports.__esModule = true;
-});
+});
\ No newline at end of file
diff --git a/test/fixtures/transformation/es7-abstract-references/private/expected.js b/test/fixtures/transformation/es7-abstract-references/private/expected.js
index 1af25539ca..08e3dde5f8 100644
--- a/test/fixtures/transformation/es7-abstract-references/private/expected.js
+++ b/test/fixtures/transformation/es7-abstract-references/private/expected.js
@@ -1,5 +1,7 @@
 "use strict";
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var A = new WeakMap();
 var B = new WeakMap(),
     C = new WeakMap();
@@ -7,7 +9,9 @@ var D = (function () {
   var F = new WeakMap(),
       G = new WeakMap();
   var E = new WeakMap();
-  function D() {}
+  function D() {
+    _classCallCheck(this, D);
+  }
 
   return D;
 })();
@@ -16,7 +20,9 @@ var H = (function () {
   var J = new WeakMap(),
       K = new WeakMap();
   var I = new WeakMap();
-  function H() {}
+  function H() {
+    _classCallCheck(this, H);
+  }
 
   return H;
-})();
+})();
\ No newline at end of file
diff --git a/test/fixtures/transformation/playground/object-getter-memoization/expected.js b/test/fixtures/transformation/playground/object-getter-memoization/expected.js
index 6476a64b68..00f7966f7b 100644
--- a/test/fixtures/transformation/playground/object-getter-memoization/expected.js
+++ b/test/fixtures/transformation/playground/object-getter-memoization/expected.js
@@ -2,10 +2,14 @@
 
 var _prototypeProperties = function (child, staticProps, instanceProps) { if (staticProps) Object.defineProperties(child, staticProps); if (instanceProps) Object.defineProperties(child.prototype, instanceProps); };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var _defineProperty = function (obj, key, value) { return Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); };
 
 var Foo = (function () {
-  function Foo() {}
+  function Foo() {
+    _classCallCheck(this, Foo);
+  }
 
   _prototypeProperties(Foo, null, _defineProperty({
     bar: {
diff --git a/test/fixtures/transformation/source-maps/class/expected.js b/test/fixtures/transformation/source-maps/class/expected.js
index 40b4dc7220..f559425ef5 100644
--- a/test/fixtures/transformation/source-maps/class/expected.js
+++ b/test/fixtures/transformation/source-maps/class/expected.js
@@ -2,8 +2,12 @@
 
 var _prototypeProperties = function (child, staticProps, instanceProps) { if (staticProps) Object.defineProperties(child, staticProps); if (instanceProps) Object.defineProperties(child.prototype, instanceProps); };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Test = (function () {
-  function Test() {}
+  function Test() {
+    _classCallCheck(this, Test);
+  }
 
   _prototypeProperties(Test, null, {
     bar: {
diff --git a/test/fixtures/transformation/spec-proto-to-assign/class/expected.js b/test/fixtures/transformation/spec-proto-to-assign/class/expected.js
index cec2fa5ac4..6217651685 100644
--- a/test/fixtures/transformation/spec-proto-to-assign/class/expected.js
+++ b/test/fixtures/transformation/spec-proto-to-assign/class/expected.js
@@ -2,13 +2,17 @@
 
 var _defaults = function (obj, defaults) { for (var key in defaults) { if (obj[key] === undefined) { obj[key] = defaults[key]; } } return obj; };
 
+var _classSuperConstructorCall = function (Constructor) { if (Object.getPrototypeOf(Constructor) !== null) { Object.getPrototypeOf(Constructor).apply(this, arguments); } };
+
 var _inherits = function (subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) _defaults(subClass, superClass); };
 
+var _classCallCheck = function (instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } };
+
 var Foo = (function (Bar) {
   function Foo() {
-    if (Object.getPrototypeOf(Foo) !== null) {
-      Object.getPrototypeOf(Foo).apply(this, arguments);
-    }
+    _classCallCheck(this, Foo);
+
+    _classSuperConstructorCall(Foo);
   }
 
   _inherits(Foo, Bar);