diff --git a/lib/6to5/transformation/transformers/es6-classes.js b/lib/6to5/transformation/transformers/es6-classes.js
index 31b3ca8843..e405ab761d 100644
--- a/lib/6to5/transformation/transformers/es6-classes.js
+++ b/lib/6to5/transformation/transformers/es6-classes.js
@@ -21,7 +21,7 @@ exports.ClassDeclaration = function (node, parent, file, scope) {
       });
       return t.assignmentExpression("=", node.id, newNode);
     } else {
-      // likely has a PrivateDeclaration etc
+      // has a super class or PrivateDeclaration etc
       return t.variableDeclaration("let", [
         t.variableDeclarator(node.id, newNode)
       ]);
@@ -85,7 +85,8 @@ Class.prototype.run = function () {
 
   //
 
-  if (superName && t.isDynamic(superName)) {
+  if (superName) {
+    this.closure = true;
     // so we're only evaluating it once
     var superRefName = "super";
     if (className) superRefName = className.name + "Super";
@@ -95,13 +96,8 @@ Class.prototype.run = function () {
       t.variableDeclarator(superRef, superName)
     ]));
     superName = superRef;
-  }
 
-  this.superName = superName;
-
-  //
-
-  if (superName) {
+    this.superName = superName;
     body.push(t.expressionStatement(t.callExpression(file.addDeclaration("inherits"), [className, superName])));
   }
 
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 fd7527b70a..66577c1cc1 100644
--- a/test/fixtures/transformation/es6-classes/accessing-super-class/expected.js
+++ b/test/fixtures/transformation/es6-classes/accessing-super-class/expected.js
@@ -13,29 +13,34 @@ var _inherits = function (child, parent) {
   if (parent) child.__proto__ = parent;
 };
 
-var Test = function Test() {
-  woops["super"].test();
-  Foo.call(this);
-  Foo.prototype.test.call(this);
-  foob(Foo);
+var Test = (function () {
+  var _TestSuper = Foo;
+  var Test = function Test() {
+    woops["super"].test();
+    _TestSuper.call(this);
+    _TestSuper.prototype.test.call(this);
+    foob(_TestSuper);
 
-  Foo.call.apply(Foo, [this].concat(_slice.call(arguments)));
-  Foo.call.apply(Foo, [this, "test"].concat(_slice.call(arguments)));
+    _TestSuper.call.apply(_TestSuper, [this].concat(_slice.call(arguments)));
+    _TestSuper.call.apply(_TestSuper, [this, "test"].concat(_slice.call(arguments)));
 
-  Foo.prototype.test.call.apply(Foo.prototype, [this].concat(_slice.call(arguments)));
-  Foo.prototype.test.call.apply(Foo.prototype, [this, "test"].concat(_slice.call(arguments)));
-};
+    _TestSuper.prototype.test.call.apply(_TestSuper.prototype, [this].concat(_slice.call(arguments)));
+    _TestSuper.prototype.test.call.apply(_TestSuper.prototype, [this, "test"].concat(_slice.call(arguments)));
+  };
 
-_inherits(Test, Foo);
+  _inherits(Test, _TestSuper);
 
-Test.prototype.test = function () {
-  Foo.prototype.test.call(this);
-  Foo.prototype.test.call.apply(Foo.prototype.test, [this].concat(_slice.call(arguments)));
-  Foo.prototype.test.call.apply(Foo.prototype.test, [this, "test"].concat(_slice.call(arguments)));
-};
+  Test.prototype.test = function () {
+    _TestSuper.prototype.test.call(this);
+    _TestSuper.prototype.test.call.apply(_TestSuper.prototype.test, [this].concat(_slice.call(arguments)));
+    _TestSuper.prototype.test.call.apply(_TestSuper.prototype.test, [this, "test"].concat(_slice.call(arguments)));
+  };
 
-Test.foo = function () {
-  Foo.foo.call(this);
-  Foo.foo.call.apply(Foo.foo, [this].concat(_slice.call(arguments)));
-  Foo.foo.call.apply(Foo.foo, [this, "test"].concat(_slice.call(arguments)));
-};
+  Test.foo = function () {
+    _TestSuper.foo.call(this);
+    _TestSuper.foo.call.apply(_TestSuper.foo, [this].concat(_slice.call(arguments)));
+    _TestSuper.foo.call.apply(_TestSuper.foo, [this, "test"].concat(_slice.call(arguments)));
+  };
+
+  return Test;
+})();
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 64df221c08..46d9bf1c41 100644
--- a/test/fixtures/transformation/es6-classes/accessing-super-properties/expected.js
+++ b/test/fixtures/transformation/es6-classes/accessing-super-properties/expected.js
@@ -12,9 +12,14 @@ var _inherits = function (child, parent) {
   if (parent) child.__proto__ = parent;
 };
 
-var Test = function Test() {
-  Foo.prototype.test;
-  Foo.prototype.test.whatever;
-};
+var Test = (function () {
+  var _TestSuper = Foo;
+  var Test = function Test() {
+    _TestSuper.prototype.test;
+    _TestSuper.prototype.test.whatever;
+  };
 
-_inherits(Test, Foo);
+  _inherits(Test, _TestSuper);
+
+  return Test;
+})();
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 d13ee876cd..44f086c4b9 100644
--- a/test/fixtures/transformation/es6-classes/calling-super-properties/expected.js
+++ b/test/fixtures/transformation/es6-classes/calling-super-properties/expected.js
@@ -12,13 +12,18 @@ var _inherits = function (child, parent) {
   if (parent) child.__proto__ = parent;
 };
 
-var Test = function Test() {
-  Foo.prototype.test.whatever();
-  Foo.prototype.test.call(this);
-};
+var Test = (function () {
+  var _TestSuper = Foo;
+  var Test = function Test() {
+    _TestSuper.prototype.test.whatever();
+    _TestSuper.prototype.test.call(this);
+  };
 
-_inherits(Test, Foo);
+  _inherits(Test, _TestSuper);
 
-Test.test = function () {
-  return Foo.wow.call(this);
-};
+  Test.test = function () {
+    return _TestSuper.wow.call(this);
+  };
+
+  return Test;
+})();
diff --git a/test/fixtures/transformation/es6-classes/constructor/expected.js b/test/fixtures/transformation/es6-classes/constructor/expected.js
index 00e97931b5..c6b5282782 100644
--- a/test/fixtures/transformation/es6-classes/constructor/expected.js
+++ b/test/fixtures/transformation/es6-classes/constructor/expected.js
@@ -16,8 +16,13 @@ var Test = function Test() {
   this.state = "test";
 };
 
-var Foo = function Foo() {
-  this.state = "test";
-};
+var Foo = (function () {
+  var _FooSuper = Bar;
+  var Foo = function Foo() {
+    this.state = "test";
+  };
 
-_inherits(Foo, Bar);
+  _inherits(Foo, _FooSuper);
+
+  return Foo;
+})();
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 70de0712ea..cc5ebdee6f 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
@@ -12,18 +12,28 @@ var _inherits = function (child, parent) {
   if (parent) child.__proto__ = parent;
 };
 
-var BaseController = function BaseController() {
-  if (Chaplin.Controller) {
-    Chaplin.Controller.apply(this, arguments);
-  }
-};
+var BaseController = (function () {
+  var _BaseControllerSuper = Chaplin.Controller;
+  var BaseController = function BaseController() {
+    if (_BaseControllerSuper) {
+      _BaseControllerSuper.apply(this, arguments);
+    }
+  };
 
-_inherits(BaseController, Chaplin.Controller);
+  _inherits(BaseController, _BaseControllerSuper);
 
-var BaseController2 = function BaseController2() {
-  if (Chaplin.Controller.Another) {
-    Chaplin.Controller.Another.apply(this, arguments);
-  }
-};
+  return BaseController;
+})();
 
-_inherits(BaseController2, Chaplin.Controller.Another);
+var BaseController2 = (function () {
+  var _BaseController2Super = Chaplin.Controller.Another;
+  var BaseController2 = function BaseController2() {
+    if (_BaseController2Super) {
+      _BaseController2Super.apply(this, arguments);
+    }
+  };
+
+  _inherits(BaseController2, _BaseController2Super);
+
+  return BaseController2;
+})();
diff --git a/test/fixtures/transformation/es6-classes/super-class/expected.js b/test/fixtures/transformation/es6-classes/super-class/expected.js
index d7a906d848..8e7db71d24 100644
--- a/test/fixtures/transformation/es6-classes/super-class/expected.js
+++ b/test/fixtures/transformation/es6-classes/super-class/expected.js
@@ -12,10 +12,15 @@ var _inherits = function (child, parent) {
   if (parent) child.__proto__ = parent;
 };
 
-var Test = function Test() {
-  if (Foo) {
-    Foo.apply(this, arguments);
-  }
-};
+var Test = (function () {
+  var _TestSuper = Foo;
+  var Test = function Test() {
+    if (_TestSuper) {
+      _TestSuper.apply(this, arguments);
+    }
+  };
 
-_inherits(Test, Foo);
+  _inherits(Test, _TestSuper);
+
+  return Test;
+})();