diff --git a/.babelrc b/.babelrc
index af0f0c3d..7f8ca683 100644
--- a/.babelrc
+++ b/.babelrc
@@ -1,3 +1,4 @@
 {
-  "presets": ["es2015"]
+  "presets": ["es2015"],
+  "plugins": ["transform-object-assign"]
 }
\ No newline at end of file
diff --git a/dist/index.js b/dist/index.js
index 221a1c4b..31e13f4d 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -622,6 +622,8 @@ exports.Nodes = Nodes;
 "use strict";
 "use strict";
 
+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 _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();
 
 function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
@@ -654,7 +656,7 @@ var JavaScriptObfuscator = function () {
     }, {
         key: 'generateCode',
         value: function generateCode(astTree, options) {
-            var escodegenParams = Object.assign({}, JavaScriptObfuscator.escodegenParams);
+            var escodegenParams = _extends({}, JavaScriptObfuscator.escodegenParams);
             escodegenParams.format = {
                 compact: options.get('compact')
             };
@@ -957,6 +959,8 @@ exports.Obfuscator = Obfuscator;
 "use strict";
 "use strict";
 
+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 _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();
 
 function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
@@ -968,7 +972,7 @@ var Options = function () {
     function Options(options) {
         _classCallCheck(this, Options);
 
-        this.options = Object.freeze(OptionsNormalizer_1.OptionsNormalizer.normalizeOptionsPreset(Object.assign({}, DefaultPreset_1.DEFAULT_PRESET, options)));
+        this.options = Object.freeze(OptionsNormalizer_1.OptionsNormalizer.normalizeOptionsPreset(_extends({}, DefaultPreset_1.DEFAULT_PRESET, options)));
     }
 
     _createClass(Options, [{
@@ -990,6 +994,8 @@ exports.Options = Options;
 "use strict";
 "use strict";
 
+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 _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();
 
 function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
@@ -1002,7 +1008,7 @@ var OptionsNormalizer = function () {
     _createClass(OptionsNormalizer, null, [{
         key: 'normalizeOptionsPreset',
         value: function normalizeOptionsPreset(options) {
-            var normalizedOptions = Object.assign({}, options);
+            var normalizedOptions = _extends({}, options);
             normalizedOptions = OptionsNormalizer.unicodeArrayRule(normalizedOptions);
             normalizedOptions = OptionsNormalizer.unicodeArrayThresholdRule(normalizedOptions);
             normalizedOptions = OptionsNormalizer.selfDefendingRule(normalizedOptions);
@@ -1012,7 +1018,7 @@ var OptionsNormalizer = function () {
         key: 'selfDefendingRule',
         value: function selfDefendingRule(options) {
             if (options['selfDefending']) {
-                Object.assign(options, OptionsNormalizer.SELF_DEFENDING_OPTIONS);
+                _extends(options, OptionsNormalizer.SELF_DEFENDING_OPTIONS);
             }
             return options;
         }
@@ -1020,7 +1026,7 @@ var OptionsNormalizer = function () {
         key: 'unicodeArrayRule',
         value: function unicodeArrayRule(options) {
             if (!options['unicodeArray']) {
-                Object.assign(options, OptionsNormalizer.DISABLED_UNICODE_ARRAY_OPTIONS);
+                _extends(options, OptionsNormalizer.DISABLED_UNICODE_ARRAY_OPTIONS);
             }
             return options;
         }
@@ -1057,6 +1063,8 @@ exports.OptionsNormalizer = OptionsNormalizer;
 "use strict";
 "use strict";
 
+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 _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();
 
 function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
@@ -1104,7 +1112,7 @@ var JavaScriptObfuscatorCLI = function () {
                 }
                 options[option] = this.commands[option];
             }
-            return Object.assign({}, DefaultPreset_1.DEFAULT_PRESET, options);
+            return _extends({}, DefaultPreset_1.DEFAULT_PRESET, options);
         }
     }, {
         key: 'configureCommands',
@@ -2278,6 +2286,8 @@ exports.LiteralObfuscator = LiteralObfuscator;
 
 var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) { return typeof obj; } : function (obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol ? "symbol" : typeof obj; };
 
+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 _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();
 
 function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
@@ -2336,7 +2346,7 @@ var MemberExpressionObfuscator = function (_NodeObfuscator_1$Nod) {
                 value: nodeValue
             };
             delete node.name;
-            Object.assign(node, literalNode);
+            _extends(node, literalNode);
         }
     }, {
         key: 'obfuscateLiteralProperty',
@@ -2435,6 +2445,8 @@ exports.MethodDefinitionObfuscator = MethodDefinitionObfuscator;
 "use strict";
 "use strict";
 
+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 _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) { return typeof obj; } : function (obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol ? "symbol" : typeof obj; };
 
 var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();
@@ -2511,7 +2523,7 @@ var ObjectExpressionObfuscator = function (_NodeObfuscator_1$Nod) {
                 value: nodeValue
             };
             delete node.name;
-            Object.assign(node, literalNode);
+            _extends(node, literalNode);
         }
     }]);
 
diff --git a/package.json b/package.json
index 41037d9d..be173f26 100644
--- a/package.json
+++ b/package.json
@@ -27,6 +27,7 @@
   "devDependencies": {
     "babel-cli": "^6.9.0",
     "babel-loader": "^6.2.4",
+    "babel-plugin-transform-object-assign": "^6.8.0",
     "babel-preset-es2015": "^6.9.0",
     "chai": "^3.5.0",
     "coveralls": "^2.11.9",
@@ -34,7 +35,7 @@
     "mocha": "^2.5.3",
     "sinon": "^1.17.4",
     "ts-loader": "^0.8.2",
-    "ts-node": "^0.9.1",
+    "ts-node": "^0.9.3",
     "tslint": "^3.12.1",
     "typescript": "^1.8.10",
     "typings": "^1.3.0",
diff --git a/scripts/test-compile b/scripts/test-compile
index 8dc2aae9..d36bcdf6 100755
--- a/scripts/test-compile
+++ b/scripts/test-compile
@@ -1,4 +1,4 @@
 #!/bin/bash
 
 $(npm bin)/tsc -p tsconfig-test.json
-$(npm bin)/babel test-tmp --out-dir test-tmp --source-maps
\ No newline at end of file
+$(npm bin)/babel test-tmp --out-dir test-tmp --source-maps --presets es2015 --plugins transform-object-assign
\ No newline at end of file
diff --git a/scripts/test-dev b/scripts/test-dev
index 26921881..9859cff9 100755
--- a/scripts/test-dev
+++ b/scripts/test-dev
@@ -1,3 +1,3 @@
 #!/bin/bash
 
-node test/dev/test.js
\ No newline at end of file
+$(npm bin)/ts-node test/dev/test.ts
\ No newline at end of file
diff --git a/test/dev/test.js b/test/dev/test.ts
similarity index 91%
rename from test/dev/test.js
rename to test/dev/test.ts
index 7736000d..27d308e1 100644
--- a/test/dev/test.js
+++ b/test/dev/test.ts
@@ -1,8 +1,8 @@
 'use strict';
 
-let JavaScriptObfuscator = require('../../dist/index');
+let JavaScriptObfuscator: any = require('../../dist/index');
 
-let obfuscatedCode = JavaScriptObfuscator.obfuscate(
+let obfuscatedCode: string = JavaScriptObfuscator.obfuscate(
     `
     (function(){
         var result = 1,