diff --git a/lib/6to5/transformation/templates/class-super-constructor-call.js b/lib/6to5/transformation/templates/class-super-constructor-call.js
index c50d3a50cc..c9b822f013 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 (SUPER_NAME) {
+if (SUPER_NAME !== null) {
   SUPER_NAME.apply(this, arguments);
 }
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 3e58ae4cf4..a3dc10057d 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
@@ -15,7 +15,7 @@ var _inherits = function (child, parent) {
 var BaseController = (function () {
   var _Chaplin$Controller = Chaplin.Controller;
   var BaseController = function BaseController() {
-    if (_Chaplin$Controller) {
+    if (_Chaplin$Controller !== null) {
       _Chaplin$Controller.apply(this, arguments);
     }
   };
@@ -28,7 +28,7 @@ var BaseController = (function () {
 var BaseController2 = (function () {
   var _Chaplin$Controller$Another = Chaplin.Controller.Another;
   var BaseController2 = function BaseController2() {
-    if (_Chaplin$Controller$Another) {
+    if (_Chaplin$Controller$Another !== null) {
       _Chaplin$Controller$Another.apply(this, arguments);
     }
   };
diff --git a/test/fixtures/transformation/es6-classes/super-class/expected.js b/test/fixtures/transformation/es6-classes/super-class/expected.js
index d57ed0b72c..50b689e121 100644
--- a/test/fixtures/transformation/es6-classes/super-class/expected.js
+++ b/test/fixtures/transformation/es6-classes/super-class/expected.js
@@ -15,7 +15,7 @@ var _inherits = function (child, parent) {
 var Test = (function () {
   var _Foo = Foo;
   var Test = function Test() {
-    if (_Foo) {
+    if (_Foo !== null) {
       _Foo.apply(this, arguments);
     }
   };
diff --git a/test/fixtures/transformation/optional-proto-to-assign/class/expected.js b/test/fixtures/transformation/optional-proto-to-assign/class/expected.js
index 2f4501d427..2af2a9b699 100644
--- a/test/fixtures/transformation/optional-proto-to-assign/class/expected.js
+++ b/test/fixtures/transformation/optional-proto-to-assign/class/expected.js
@@ -25,7 +25,7 @@ var _inherits = function (child, parent) {
 var Foo = (function () {
   var _Bar = Bar;
   var Foo = function Foo() {
-    if (_Bar) {
+    if (_Bar !== null) {
       _Bar.apply(this, arguments);
     }
   };