diff --git a/lib/6to5/file.js b/lib/6to5/file.js
index cd2d34a6ac..59ec12ef3f 100644
--- a/lib/6to5/file.js
+++ b/lib/6to5/file.js
@@ -183,6 +183,7 @@ File.prototype.buildTransformers = function () {
 
     if (pass.canRun(file)) {
       stack.push(pass);
+
       if (transformer.secondPass) {
         secondaryStack.push(pass);
       }
diff --git a/lib/6to5/transformation/helpers/replace-supers.js b/lib/6to5/transformation/helpers/replace-supers.js
index 12d894d764..0931e52e64 100644
--- a/lib/6to5/transformation/helpers/replace-supers.js
+++ b/lib/6to5/transformation/helpers/replace-supers.js
@@ -38,12 +38,7 @@ ReplaceSupers.prototype.setSuperProperty = function (property, value, isStatic,
   return t.callExpression(
     this.file.addHelper("set"),
     [
-      t.callExpression(
-        t.memberExpression(t.identifier("Object"), t.identifier("getPrototypeOf")),
-        [
-          isStatic ? this.className : t.memberExpression(this.className, t.identifier("prototype"))
-        ]
-      ),
+      isStatic ? this.superName : t.memberExpression(this.superName, t.identifier("prototype")),
       isComputed ? property : t.literal(property.name),
       value,
       thisExpression
@@ -65,63 +60,17 @@ ReplaceSupers.prototype.setSuperProperty = function (property, value, isStatic,
  * @returns {Node}
  */
 
-ReplaceSupers.prototype.superProperty = function (property, isStatic, isComputed, thisExpression) {
+ReplaceSupers.prototype.getSuperProperty = function (property, isStatic, isComputed, thisExpression) {
   return t.callExpression(
     this.file.addHelper("get"),
     [
-      t.callExpression(
-        t.memberExpression(t.identifier("Object"), t.identifier("getPrototypeOf")),
-        [
-          isStatic ? this.className : t.memberExpression(this.className, t.identifier("prototype"))
-        ]
-      ),
+      isStatic ? this.superName : t.memberExpression(this.superName, t.identifier("prototype")),
       isComputed ? property : t.literal(property.name),
       thisExpression
     ]
   );
 };
 
-/**
- * Description
- *
- * @param {Object} node
- * @param {Object} id
- * @param {Object} parent
- * @returns {Object}
- */
-
-ReplaceSupers.prototype.looseSuperProperty = function (methodNode, id, parent) {
-  var methodName = methodNode.key;
-  var superName  = this.superName || t.identifier("Function");
-
-  if (parent.property === id) {
-    return;
-  } else if (t.isCallExpression(parent, { callee: id })) {
-    // super(); -> ClassName.prototype.MethodName.call(this);
-    parent.arguments.unshift(t.thisExpression());
-
-    if (methodName.name === "constructor") {
-      // constructor() { super(); }
-      return t.memberExpression(superName, t.identifier("call"));
-    } else {
-      id = superName;
-
-      // foo() { super(); }
-      if (!methodNode.static) {
-        id = t.memberExpression(id, t.identifier("prototype"));
-      }
-
-      id = t.memberExpression(id, methodName, methodNode.computed);
-      return t.memberExpression(id, t.identifier("call"));
-    }
-  } else if (t.isMemberExpression(parent) && !methodNode.static) {
-    // super.test -> ClassName.prototype.test
-    return t.memberExpression(superName, t.identifier("prototype"));
-  } else {
-    return superName;
-  }
-};
-
 /**
  * Description
  */
@@ -186,6 +135,47 @@ ReplaceSupers.prototype.getThisReference = function () {
   }
 };
 
+/**
+ * Description
+ *
+ * @param {Object} node
+ * @param {Object} id
+ * @param {Object} parent
+ * @returns {Object}
+ */
+
+ReplaceSupers.prototype.getLooseSuperProperty = function (methodNode, id, parent) {
+  var methodName = methodNode.key;
+  var superName  = this.superName || t.identifier("Function");
+
+  if (parent.property === id) {
+    return;
+  } else if (t.isCallExpression(parent, { callee: id })) {
+    // super(); -> ClassName.prototype.MethodName.call(this);
+    parent.arguments.unshift(t.thisExpression());
+
+    if (methodName.name === "constructor") {
+      // constructor() { super(); }
+      return t.memberExpression(superName, t.identifier("call"));
+    } else {
+      id = superName;
+
+      // foo() { super(); }
+      if (!methodNode.static) {
+        id = t.memberExpression(id, t.identifier("prototype"));
+      }
+
+      id = t.memberExpression(id, methodName, methodNode.computed);
+      return t.memberExpression(id, t.identifier("call"));
+    }
+  } else if (t.isMemberExpression(parent) && !methodNode.static) {
+    // super.test -> ClassName.prototype.test
+    return t.memberExpression(superName, t.identifier("prototype"));
+  } else {
+    return superName;
+  }
+};
+
 /**
  * Description
  *
@@ -196,7 +186,7 @@ ReplaceSupers.prototype.getThisReference = function () {
 
 ReplaceSupers.prototype.looseHandle = function (getThisReference, node, parent) {
   if (t.isIdentifier(node, { name: "super" })) {
-    return this.looseSuperProperty(this.methodNode, node, parent);
+    return this.getLooseSuperProperty(this.methodNode, node, parent);
   } else if (t.isCallExpression(node)) {
     var callee = node.callee;
     if (!t.isMemberExpression(callee)) return;
@@ -269,7 +259,7 @@ ReplaceSupers.prototype.specHandle = function (getThisReference, node, parent) {
   if (!property) return;
 
   thisReference = getThisReference();
-  var superProperty = this.superProperty(property, methodNode.static, computed, thisReference);
+  var superProperty = this.getSuperProperty(property, methodNode.static, computed, thisReference);
   if (args) {
     if (args.length === 1 && t.isSpreadElement(args[0])) {
       // super(...arguments);
diff --git a/lib/6to5/transformation/templates/class-super-constructor-call.js b/lib/6to5/transformation/templates/class-super-constructor-call.js
index 21034b6201..ab957160f2 100644
--- a/lib/6to5/transformation/templates/class-super-constructor-call.js
+++ b/lib/6to5/transformation/templates/class-super-constructor-call.js
@@ -1,3 +1,3 @@
-if (Object.getPrototypeOf(CLASS_NAME) !== null) {
-  Object.getPrototypeOf(CLASS_NAME).apply(this, arguments);
+if (SUPER_NAME != null) {
+  SUPER_NAME.apply(this, arguments);
 }
diff --git a/lib/6to5/transformation/transformers/es6/classes.js b/lib/6to5/transformation/transformers/es6/classes.js
index 61e906ca62..d45297f4d9 100644
--- a/lib/6to5/transformation/transformers/es6/classes.js
+++ b/lib/6to5/transformation/transformers/es6/classes.js
@@ -50,7 +50,8 @@ function Class(node, file, scope, isStatement) {
   this.staticMutatorMap   = {};
   this.hasConstructor     = false;
   this.className          = node.id || scope.generateUidIdentifier("class");
-  this.superName          = node.superClass;
+  this.superName          = node.superClass || t.identifier("Function");
+  this.hasSuper           = !!node.superClass;
   this.isLoose            = file.isLoose("es6.classes");
 }
 
@@ -93,7 +94,7 @@ Class.prototype.run = function () {
 
   //
 
-  if (superName) {
+  if (this.hasSuper) {
     closureArgs.push(superName);
 
     if (!t.isIdentifier(superName)) {
@@ -169,7 +170,7 @@ 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)) {
+  if (!this.hasConstructor && this.hasSuper && !t.isFalsyExpression(superName)) {
     var helperName = "class-super-constructor-call";
     if (this.isLoose) helperName += "-loose";
     constructor.body.body.push(util.template(helperName, {
diff --git a/lib/6to5/transformation/transformers/es7/object-rest-spread.js b/lib/6to5/transformation/transformers/es7/object-rest-spread.js
index 2667946edd..f70d9572e7 100644
--- a/lib/6to5/transformation/transformers/es7/object-rest-spread.js
+++ b/lib/6to5/transformation/transformers/es7/object-rest-spread.js
@@ -7,7 +7,7 @@ var t = require("../../../types");
 exports.experimental = true;
 
 exports.manipulateOptions = function (opts) {
-  opts.whitelist.push("es6.destructuring");
+  if (opts.whitelist.length) opts.whitelist.push("es6.destructuring");
 };
 
 var hasSpread = function (node) {
diff --git a/test/fixtures/esnext/es6-classes/super-change-proto.js b/test/fixtures/esnext/es6-classes/super-change-proto.js
deleted file mode 100644
index 01058549c9..0000000000
--- a/test/fixtures/esnext/es6-classes/super-change-proto.js
+++ /dev/null
@@ -1,21 +0,0 @@
-var log = '';
-
-class Base {
-  p() { log += '[Base]'; }
-}
-
-class OtherBase {
-  p() { log += '[OtherBase]'; }
-}
-
-class Derived extends Base {
-  p() {
-    log += '[Derived]';
-    super.p();
-    Derived.prototype.__proto__ = OtherBase.prototype;
-    super.p();
-  }
-}
-
-new Derived().p();
-assert.equal(log, '[Derived][Base][OtherBase]');
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 a8f74b0cb7..7f6a1389dc 100644
--- a/test/fixtures/transformation/es6-classes/accessing-super-class/expected.js
+++ b/test/fixtures/transformation/es6-classes/accessing-super-class/expected.js
@@ -15,14 +15,14 @@ var Test = (function (Foo) {
     _classCallCheck(this, Test);
 
     woops["super"].test();
-    _get(Object.getPrototypeOf(Test.prototype), "constructor", this).call(this);
-    _get(Object.getPrototypeOf(Test.prototype), "test", this).call(this);
+    _get(Foo.prototype, "constructor", this).call(this);
+    _get(Foo.prototype, "test", this).call(this);
 
-    _get(Object.getPrototypeOf(Test.prototype), "constructor", this).apply(this, arguments);
-    (_get2 = _get(Object.getPrototypeOf(Test.prototype), "constructor", this)).call.apply(_get2, [this, "test"].concat(_slice.call(arguments)));
+    _get(Foo.prototype, "constructor", this).apply(this, arguments);
+    (_get2 = _get(Foo.prototype, "constructor", this)).call.apply(_get2, [this, "test"].concat(_slice.call(arguments)));
 
-    _get(Object.getPrototypeOf(Test.prototype), "test", this).apply(this, arguments);
-    (_get3 = _get(Object.getPrototypeOf(Test.prototype), "test", this)).call.apply(_get3, [this, "test"].concat(_slice.call(arguments)));
+    _get(Foo.prototype, "test", this).apply(this, arguments);
+    (_get3 = _get(Foo.prototype, "test", this)).call.apply(_get3, [this, "test"].concat(_slice.call(arguments)));
   }
 
   _inherits(Test, Foo);
@@ -31,9 +31,9 @@ var Test = (function (Foo) {
     foo: {
       value: function foo() {
         var _get2;
-        _get(Object.getPrototypeOf(Test), "foo", this).call(this);
-        _get(Object.getPrototypeOf(Test), "foo", this).apply(this, arguments);
-        (_get2 = _get(Object.getPrototypeOf(Test), "foo", this)).call.apply(_get2, [this, "test"].concat(_slice.call(arguments)));
+        _get(Foo, "foo", this).call(this);
+        _get(Foo, "foo", this).apply(this, arguments);
+        (_get2 = _get(Foo, "foo", this)).call.apply(_get2, [this, "test"].concat(_slice.call(arguments)));
       },
       writable: true,
       configurable: true
@@ -42,9 +42,9 @@ var Test = (function (Foo) {
     test: {
       value: function test() {
         var _get2;
-        _get(Object.getPrototypeOf(Test.prototype), "test", this).call(this);
-        _get(Object.getPrototypeOf(Test.prototype), "test", this).apply(this, arguments);
-        (_get2 = _get(Object.getPrototypeOf(Test.prototype), "test", this)).call.apply(_get2, [this, "test"].concat(_slice.call(arguments)));
+        _get(Foo.prototype, "test", this).call(this);
+        _get(Foo.prototype, "test", this).apply(this, arguments);
+        (_get2 = _get(Foo.prototype, "test", this)).call.apply(_get2, [this, "test"].concat(_slice.call(arguments)));
       },
       writable: true,
       configurable: true
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 7ee14a53f1..9112ab7d1d 100644
--- a/test/fixtures/transformation/es6-classes/accessing-super-properties/expected.js
+++ b/test/fixtures/transformation/es6-classes/accessing-super-properties/expected.js
@@ -10,8 +10,8 @@ var Test = (function (Foo) {
   function Test() {
     _classCallCheck(this, Test);
 
-    _get(Object.getPrototypeOf(Test.prototype), "test", this);
-    _get(Object.getPrototypeOf(Test.prototype), "test", this).whatever;
+    _get(Foo.prototype, "test", this);
+    _get(Foo.prototype, "test", this).whatever;
   }
 
   _inherits(Test, Foo);
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 4ae369971d..e0fcb1292a 100644
--- a/test/fixtures/transformation/es6-classes/calling-super-properties/expected.js
+++ b/test/fixtures/transformation/es6-classes/calling-super-properties/expected.js
@@ -12,8 +12,8 @@ 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);
+    _get(Foo.prototype, "test", this).whatever();
+    _get(Foo.prototype, "test", this).call(this);
   }
 
   _inherits(Test, Foo);
@@ -21,7 +21,7 @@ var Test = (function (Foo) {
   _prototypeProperties(Test, {
     test: {
       value: function test() {
-        return _get(Object.getPrototypeOf(Test), "wow", this).call(this);
+        return _get(Foo, "wow", this).call(this);
       },
       writable: true,
       configurable: true
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 70caacde0a..e277b544fd 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
@@ -8,8 +8,8 @@ var BaseController = (function (_Chaplin$Controller) {
   function BaseController() {
     _classCallCheck(this, BaseController);
 
-    if (Object.getPrototypeOf(BaseController) !== null) {
-      Object.getPrototypeOf(BaseController).apply(this, arguments);
+    if (_Chaplin$Controller != null) {
+      _Chaplin$Controller.apply(this, arguments);
     }
   }
 
@@ -22,12 +22,12 @@ var BaseController2 = (function (_Chaplin$Controller$Another) {
   function BaseController2() {
     _classCallCheck(this, BaseController2);
 
-    if (Object.getPrototypeOf(BaseController2) !== null) {
-      Object.getPrototypeOf(BaseController2).apply(this, arguments);
+    if (_Chaplin$Controller$Another != null) {
+      _Chaplin$Controller$Another.apply(this, arguments);
     }
   }
 
   _inherits(BaseController2, _Chaplin$Controller$Another);
 
   return BaseController2;
-})(Chaplin.Controller.Another);
+})(Chaplin.Controller.Another);
\ No newline at end of file
diff --git a/test/fixtures/transformation/es6-classes/super-class/expected.js b/test/fixtures/transformation/es6-classes/super-class/expected.js
index aec7b613ab..338d66b696 100644
--- a/test/fixtures/transformation/es6-classes/super-class/expected.js
+++ b/test/fixtures/transformation/es6-classes/super-class/expected.js
@@ -8,12 +8,12 @@ var Test = (function (Foo) {
   function Test() {
     _classCallCheck(this, Test);
 
-    if (Object.getPrototypeOf(Test) !== null) {
-      Object.getPrototypeOf(Test).apply(this, arguments);
+    if (Foo != null) {
+      Foo.apply(this, arguments);
     }
   }
 
   _inherits(Test, Foo);
 
   return Test;
-})(Foo);
+})(Foo);
\ No newline at end of file
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 e278a09b33..13bf3b8d41 100644
--- a/test/fixtures/transformation/es6-classes/super-function-fallback/expected.js
+++ b/test/fixtures/transformation/es6-classes/super-function-fallback/expected.js
@@ -7,5 +7,5 @@ var _classCallCheck = function (instance, Constructor) { if (!(instance instance
 var Test = function Test() {
   _classCallCheck(this, Test);
 
-  _get(Object.getPrototypeOf(Test.prototype), "hasOwnProperty", this).call(this, "test");
-};
\ No newline at end of file
+  _get(Function.prototype, "hasOwnProperty", this).call(this, "test");
+};
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 22b7ef21ef..4b47fef537 100644
--- a/test/fixtures/transformation/spec-proto-to-assign/class/expected.js
+++ b/test/fixtures/transformation/spec-proto-to-assign/class/expected.js
@@ -10,12 +10,12 @@ var Foo = (function (Bar) {
   function Foo() {
     _classCallCheck(this, Foo);
 
-    if (Object.getPrototypeOf(Foo) !== null) {
-      Object.getPrototypeOf(Foo).apply(this, arguments);
+    if (Bar != null) {
+      Bar.apply(this, arguments);
     }
   }
 
   _inherits(Foo, Bar);
 
   return Foo;
-})(Bar);
+})(Bar);
\ No newline at end of file