diff --git a/test/fixtures/transformation/es7-object-spread/assignment/expected.js b/test/fixtures/transformation/es7-object-spread/assignment/expected.js
index 7768f0f858..55e8e562b3 100644
--- a/test/fixtures/transformation/es7-object-spread/assignment/expected.js
+++ b/test/fixtures/transformation/es7-object-spread/assignment/expected.js
@@ -1,5 +1,5 @@
 "use strict";
 
-var _extends = function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };
+var _extends = Object.assign || function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };
 
 z = _extends({ x: x }, y);
diff --git a/test/fixtures/transformation/es7-object-spread/expression/expected.js b/test/fixtures/transformation/es7-object-spread/expression/expected.js
index f2671698d9..6473abeefa 100644
--- a/test/fixtures/transformation/es7-object-spread/expression/expected.js
+++ b/test/fixtures/transformation/es7-object-spread/expression/expected.js
@@ -1,5 +1,5 @@
 "use strict";
 
-var _extends = function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };
+var _extends = Object.assign || function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };
 
 _extends({ x: x }, y, { a: a }, b, { c: c });
diff --git a/test/fixtures/transformation/es7-object-spread/variable-declaration/expected.js b/test/fixtures/transformation/es7-object-spread/variable-declaration/expected.js
index ceb256a198..4180a0fdb0 100644
--- a/test/fixtures/transformation/es7-object-spread/variable-declaration/expected.js
+++ b/test/fixtures/transformation/es7-object-spread/variable-declaration/expected.js
@@ -1,5 +1,5 @@
 "use strict";
 
-var _extends = function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };
+var _extends = Object.assign || function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };
 
 var z = _extends({}, x);
diff --git a/test/fixtures/transformation/react/adds-appropriate-newlines-when-using-spread-attribute/expected.js b/test/fixtures/transformation/react/adds-appropriate-newlines-when-using-spread-attribute/expected.js
index 46962e2c4b..1d60d633e3 100644
--- a/test/fixtures/transformation/react/adds-appropriate-newlines-when-using-spread-attribute/expected.js
+++ b/test/fixtures/transformation/react/adds-appropriate-newlines-when-using-spread-attribute/expected.js
@@ -1,4 +1,4 @@
-var _extends = function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };
+var _extends = Object.assign || function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };
 
 React.createElement(Component, _extends({}, props, {
   sound: "moo" }));
diff --git a/test/fixtures/transformation/react/wraps-props-in-react-spread-for-first-spread-attributes/expected.js b/test/fixtures/transformation/react/wraps-props-in-react-spread-for-first-spread-attributes/expected.js
index 4d3fb939fd..ba6253f282 100644
--- a/test/fixtures/transformation/react/wraps-props-in-react-spread-for-first-spread-attributes/expected.js
+++ b/test/fixtures/transformation/react/wraps-props-in-react-spread-for-first-spread-attributes/expected.js
@@ -1,3 +1,3 @@
-var _extends = function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };
+var _extends = Object.assign || function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };
 
 React.createElement(Component, _extends({}, x, { y: 2, z: true }));
diff --git a/test/fixtures/transformation/react/wraps-props-in-react-spread-for-last-spread-attributes/expected.js b/test/fixtures/transformation/react/wraps-props-in-react-spread-for-last-spread-attributes/expected.js
index e64b5a25f6..12571fc335 100644
--- a/test/fixtures/transformation/react/wraps-props-in-react-spread-for-last-spread-attributes/expected.js
+++ b/test/fixtures/transformation/react/wraps-props-in-react-spread-for-last-spread-attributes/expected.js
@@ -1,3 +1,3 @@
-var _extends = function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };
+var _extends = Object.assign || function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };
 
 React.createElement(Component, _extends({ y: 2, z: true }, x));
diff --git a/test/fixtures/transformation/react/wraps-props-in-react-spread-for-middle-spread-attributes/expected.js b/test/fixtures/transformation/react/wraps-props-in-react-spread-for-middle-spread-attributes/expected.js
index fff0428c83..de3276b168 100644
--- a/test/fixtures/transformation/react/wraps-props-in-react-spread-for-middle-spread-attributes/expected.js
+++ b/test/fixtures/transformation/react/wraps-props-in-react-spread-for-middle-spread-attributes/expected.js
@@ -1,3 +1,3 @@
-var _extends = function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };
+var _extends = Object.assign || function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };
 
 React.createElement(Component, _extends({ y: 2 }, x, { z: true }));
diff --git a/test/fixtures/transformation/spec-proto-to-assign/object-literal/expected.js b/test/fixtures/transformation/spec-proto-to-assign/object-literal/expected.js
index 6719a974ce..de88a93d98 100644
--- a/test/fixtures/transformation/spec-proto-to-assign/object-literal/expected.js
+++ b/test/fixtures/transformation/spec-proto-to-assign/object-literal/expected.js
@@ -1,6 +1,6 @@
 "use strict";
 
-var _extends = function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };
+var _extends = Object.assign || function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };
 
 var foo = _extends({}, bar);