diff --git a/src/ast/variables/NamespaceVariable.ts b/src/ast/variables/NamespaceVariable.ts
index 7a22234e862..10b36bdc9fb 100644
--- a/src/ast/variables/NamespaceVariable.ts
+++ b/src/ast/variables/NamespaceVariable.ts
@@ -91,6 +91,8 @@ export default class NamespaceVariable extends Variable {
 			return `${t}${safeName}: ${original.getName()}`;
 		});
 
+		members.unshift(`${t}__proto__:${_}null`);
+    
 		if (options.namespaceToStringTag) {
 			members.unshift(`${t}[Symbol.toStringTag]:${_}'Module'`);
 		}
diff --git a/test/chunking-form/samples/dynamic-import-statically-imported-2/_expected/amd/generated-dep1.js b/test/chunking-form/samples/dynamic-import-statically-imported-2/_expected/amd/generated-dep1.js
index 2ec5ef78f0c..d1ed622ba34 100644
--- a/test/chunking-form/samples/dynamic-import-statically-imported-2/_expected/amd/generated-dep1.js
+++ b/test/chunking-form/samples/dynamic-import-statically-imported-2/_expected/amd/generated-dep1.js
@@ -11,6 +11,7 @@ define(['exports'], function (exports) { 'use strict';
 	}
 
 	var dep1 = /*#__PURE__*/Object.freeze({
+		__proto__: null,
 		bar: bar
 	});
 
diff --git a/test/chunking-form/samples/dynamic-import-statically-imported-2/_expected/cjs/generated-dep1.js b/test/chunking-form/samples/dynamic-import-statically-imported-2/_expected/cjs/generated-dep1.js
index 957dd6916a7..8404868bf0f 100644
--- a/test/chunking-form/samples/dynamic-import-statically-imported-2/_expected/cjs/generated-dep1.js
+++ b/test/chunking-form/samples/dynamic-import-statically-imported-2/_expected/cjs/generated-dep1.js
@@ -11,6 +11,7 @@ function bar() {
 }
 
 var dep1 = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	bar: bar
 });
 
diff --git a/test/chunking-form/samples/dynamic-import-statically-imported-2/_expected/es/generated-dep1.js b/test/chunking-form/samples/dynamic-import-statically-imported-2/_expected/es/generated-dep1.js
index 867796fbd1d..861a4f7b643 100644
--- a/test/chunking-form/samples/dynamic-import-statically-imported-2/_expected/es/generated-dep1.js
+++ b/test/chunking-form/samples/dynamic-import-statically-imported-2/_expected/es/generated-dep1.js
@@ -9,6 +9,7 @@ function bar() {
 }
 
 var dep1 = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	bar: bar
 });
 
diff --git a/test/chunking-form/samples/dynamic-import-statically-imported-2/_expected/system/generated-dep1.js b/test/chunking-form/samples/dynamic-import-statically-imported-2/_expected/system/generated-dep1.js
index 7c01c4d8b46..f88ae2d042e 100644
--- a/test/chunking-form/samples/dynamic-import-statically-imported-2/_expected/system/generated-dep1.js
+++ b/test/chunking-form/samples/dynamic-import-statically-imported-2/_expected/system/generated-dep1.js
@@ -19,6 +19,7 @@ System.register([], function (exports) {
 			}
 
 			var dep1 = /*#__PURE__*/Object.freeze({
+				__proto__: null,
 				bar: bar
 			});
 
diff --git a/test/chunking-form/samples/dynamic-import-statically-imported/_expected/amd/generated-dep1.js b/test/chunking-form/samples/dynamic-import-statically-imported/_expected/amd/generated-dep1.js
index 2ec5ef78f0c..d1ed622ba34 100644
--- a/test/chunking-form/samples/dynamic-import-statically-imported/_expected/amd/generated-dep1.js
+++ b/test/chunking-form/samples/dynamic-import-statically-imported/_expected/amd/generated-dep1.js
@@ -11,6 +11,7 @@ define(['exports'], function (exports) { 'use strict';
 	}
 
 	var dep1 = /*#__PURE__*/Object.freeze({
+		__proto__: null,
 		bar: bar
 	});
 
diff --git a/test/chunking-form/samples/dynamic-import-statically-imported/_expected/cjs/generated-dep1.js b/test/chunking-form/samples/dynamic-import-statically-imported/_expected/cjs/generated-dep1.js
index 957dd6916a7..8404868bf0f 100644
--- a/test/chunking-form/samples/dynamic-import-statically-imported/_expected/cjs/generated-dep1.js
+++ b/test/chunking-form/samples/dynamic-import-statically-imported/_expected/cjs/generated-dep1.js
@@ -11,6 +11,7 @@ function bar() {
 }
 
 var dep1 = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	bar: bar
 });
 
diff --git a/test/chunking-form/samples/dynamic-import-statically-imported/_expected/es/generated-dep1.js b/test/chunking-form/samples/dynamic-import-statically-imported/_expected/es/generated-dep1.js
index 867796fbd1d..861a4f7b643 100644
--- a/test/chunking-form/samples/dynamic-import-statically-imported/_expected/es/generated-dep1.js
+++ b/test/chunking-form/samples/dynamic-import-statically-imported/_expected/es/generated-dep1.js
@@ -9,6 +9,7 @@ function bar() {
 }
 
 var dep1 = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	bar: bar
 });
 
diff --git a/test/chunking-form/samples/dynamic-import-statically-imported/_expected/system/generated-dep1.js b/test/chunking-form/samples/dynamic-import-statically-imported/_expected/system/generated-dep1.js
index 7c01c4d8b46..f88ae2d042e 100644
--- a/test/chunking-form/samples/dynamic-import-statically-imported/_expected/system/generated-dep1.js
+++ b/test/chunking-form/samples/dynamic-import-statically-imported/_expected/system/generated-dep1.js
@@ -19,6 +19,7 @@ System.register([], function (exports) {
 			}
 
 			var dep1 = /*#__PURE__*/Object.freeze({
+				__proto__: null,
 				bar: bar
 			});
 
diff --git a/test/chunking-form/samples/entry-point-without-own-code/_expected/amd/generated-m1.js b/test/chunking-form/samples/entry-point-without-own-code/_expected/amd/generated-m1.js
index d23351b5be1..52ed74a5c5c 100644
--- a/test/chunking-form/samples/entry-point-without-own-code/_expected/amd/generated-m1.js
+++ b/test/chunking-form/samples/entry-point-without-own-code/_expected/amd/generated-m1.js
@@ -3,6 +3,7 @@ define(['exports', './m2'], function (exports, m2) { 'use strict';
 
 
 	var ms = /*#__PURE__*/Object.freeze({
+		__proto__: null,
 		m2: m2
 	});
 
diff --git a/test/chunking-form/samples/entry-point-without-own-code/_expected/cjs/generated-m1.js b/test/chunking-form/samples/entry-point-without-own-code/_expected/cjs/generated-m1.js
index 9e827c896df..f8fc76bc360 100644
--- a/test/chunking-form/samples/entry-point-without-own-code/_expected/cjs/generated-m1.js
+++ b/test/chunking-form/samples/entry-point-without-own-code/_expected/cjs/generated-m1.js
@@ -5,6 +5,7 @@ var m2 = require('./m2.js');
 
 
 var ms = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	m2: m2
 });
 
diff --git a/test/chunking-form/samples/entry-point-without-own-code/_expected/es/generated-m1.js b/test/chunking-form/samples/entry-point-without-own-code/_expected/es/generated-m1.js
index 2feaa1ff203..eb6534be2c3 100644
--- a/test/chunking-form/samples/entry-point-without-own-code/_expected/es/generated-m1.js
+++ b/test/chunking-form/samples/entry-point-without-own-code/_expected/es/generated-m1.js
@@ -4,6 +4,7 @@ export { default as m } from './m2.js';
 
 
 var ms = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	m2: m2
 });
 
diff --git a/test/chunking-form/samples/entry-point-without-own-code/_expected/system/generated-m1.js b/test/chunking-form/samples/entry-point-without-own-code/_expected/system/generated-m1.js
index e9359f1a885..b592474ea09 100644
--- a/test/chunking-form/samples/entry-point-without-own-code/_expected/system/generated-m1.js
+++ b/test/chunking-form/samples/entry-point-without-own-code/_expected/system/generated-m1.js
@@ -11,6 +11,7 @@ System.register(['./m2.js'], function (exports) {
 
 
 			var ms = /*#__PURE__*/Object.freeze({
+				__proto__: null,
 				m2: m2
 			});
 			exports('a', ms);
diff --git a/test/chunking-form/samples/namespace-object-import/_expected/amd/generated-main2.js b/test/chunking-form/samples/namespace-object-import/_expected/amd/generated-main2.js
index 0fbd5d7082f..607a4ae6825 100644
--- a/test/chunking-form/samples/namespace-object-import/_expected/amd/generated-main2.js
+++ b/test/chunking-form/samples/namespace-object-import/_expected/amd/generated-main2.js
@@ -4,6 +4,7 @@ define(['exports'], function (exports) { 'use strict';
 	var b = 'a';
 
 	var main2 = /*#__PURE__*/Object.freeze({
+		__proto__: null,
 		a: a,
 		b: b
 	});
diff --git a/test/chunking-form/samples/namespace-object-import/_expected/cjs/generated-main2.js b/test/chunking-form/samples/namespace-object-import/_expected/cjs/generated-main2.js
index ad0cd3ad080..ed63cad59f5 100644
--- a/test/chunking-form/samples/namespace-object-import/_expected/cjs/generated-main2.js
+++ b/test/chunking-form/samples/namespace-object-import/_expected/cjs/generated-main2.js
@@ -4,6 +4,7 @@ var a = 'a';
 var b = 'a';
 
 var main2 = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	a: a,
 	b: b
 });
diff --git a/test/chunking-form/samples/namespace-object-import/_expected/es/generated-main2.js b/test/chunking-form/samples/namespace-object-import/_expected/es/generated-main2.js
index 8b1a237368b..c52fcf07ba6 100644
--- a/test/chunking-form/samples/namespace-object-import/_expected/es/generated-main2.js
+++ b/test/chunking-form/samples/namespace-object-import/_expected/es/generated-main2.js
@@ -2,6 +2,7 @@ var a = 'a';
 var b = 'a';
 
 var main2 = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	a: a,
 	b: b
 });
diff --git a/test/chunking-form/samples/namespace-object-import/_expected/system/generated-main2.js b/test/chunking-form/samples/namespace-object-import/_expected/system/generated-main2.js
index 249c51d4f16..f30d34dac44 100644
--- a/test/chunking-form/samples/namespace-object-import/_expected/system/generated-main2.js
+++ b/test/chunking-form/samples/namespace-object-import/_expected/system/generated-main2.js
@@ -7,6 +7,7 @@ System.register([], function (exports) {
 			var b = exports('b', 'a');
 
 			var main2 = /*#__PURE__*/Object.freeze({
+				__proto__: null,
 				a: a,
 				b: b
 			});
diff --git a/test/chunking-form/samples/namespace-reexport-name-conflict/_expected/amd/generated-index.js b/test/chunking-form/samples/namespace-reexport-name-conflict/_expected/amd/generated-index.js
index 8609967a094..417ce1f1d08 100644
--- a/test/chunking-form/samples/namespace-reexport-name-conflict/_expected/amd/generated-index.js
+++ b/test/chunking-form/samples/namespace-reexport-name-conflict/_expected/amd/generated-index.js
@@ -3,6 +3,7 @@ define(['exports', './generated-dep', 'external'], function (exports, dep, exter
 	console.log(external.reexported);
 
 	var lib = /*#__PURE__*/Object.freeze({
+		__proto__: null,
 		reexported: dep.reexported
 	});
 
diff --git a/test/chunking-form/samples/namespace-reexport-name-conflict/_expected/cjs/generated-index.js b/test/chunking-form/samples/namespace-reexport-name-conflict/_expected/cjs/generated-index.js
index 2615d5c1483..4c7f1ca2024 100644
--- a/test/chunking-form/samples/namespace-reexport-name-conflict/_expected/cjs/generated-index.js
+++ b/test/chunking-form/samples/namespace-reexport-name-conflict/_expected/cjs/generated-index.js
@@ -6,6 +6,7 @@ var external = require('external');
 console.log(external.reexported);
 
 var lib = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	reexported: dep.reexported
 });
 
diff --git a/test/chunking-form/samples/namespace-reexport-name-conflict/_expected/es/generated-index.js b/test/chunking-form/samples/namespace-reexport-name-conflict/_expected/es/generated-index.js
index 78e52033db5..8a2032f39bd 100644
--- a/test/chunking-form/samples/namespace-reexport-name-conflict/_expected/es/generated-index.js
+++ b/test/chunking-form/samples/namespace-reexport-name-conflict/_expected/es/generated-index.js
@@ -4,6 +4,7 @@ import { reexported } from 'external';
 console.log(reexported);
 
 var lib = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	reexported: reexported$1
 });
 
diff --git a/test/chunking-form/samples/namespace-reexport-name-conflict/_expected/system/generated-index.js b/test/chunking-form/samples/namespace-reexport-name-conflict/_expected/system/generated-index.js
index 5acfbcac078..8f6d3bfd693 100644
--- a/test/chunking-form/samples/namespace-reexport-name-conflict/_expected/system/generated-index.js
+++ b/test/chunking-form/samples/namespace-reexport-name-conflict/_expected/system/generated-index.js
@@ -12,6 +12,7 @@ System.register(['./generated-dep.js', 'external'], function (exports) {
 			console.log(reexported);
 
 			var lib = /*#__PURE__*/Object.freeze({
+				__proto__: null,
 				reexported: reexported$1
 			});
 			exports('l', lib);
diff --git a/test/chunking-form/samples/namespace-reexports/_expected/amd/generated-index.js b/test/chunking-form/samples/namespace-reexports/_expected/amd/generated-index.js
index 1337d2c2adb..f9e5cec4b44 100644
--- a/test/chunking-form/samples/namespace-reexports/_expected/amd/generated-index.js
+++ b/test/chunking-form/samples/namespace-reexports/_expected/amd/generated-index.js
@@ -5,6 +5,7 @@ define(['exports', './hsl2hsv'], function (exports, hsl2hsv$1) { 'use strict';
 	console.log(hsl2hsv);
 
 	var lib = /*#__PURE__*/Object.freeze({
+		__proto__: null,
 		hsl2hsv: hsl2hsv$1.default
 	});
 
diff --git a/test/chunking-form/samples/namespace-reexports/_expected/cjs/generated-index.js b/test/chunking-form/samples/namespace-reexports/_expected/cjs/generated-index.js
index dd171505ad1..e6feee3b2d5 100644
--- a/test/chunking-form/samples/namespace-reexports/_expected/cjs/generated-index.js
+++ b/test/chunking-form/samples/namespace-reexports/_expected/cjs/generated-index.js
@@ -7,6 +7,7 @@ var hsl2hsv = 'asdf';
 console.log(hsl2hsv);
 
 var lib = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	hsl2hsv: hsl2hsv$1.default
 });
 
diff --git a/test/chunking-form/samples/namespace-reexports/_expected/es/generated-index.js b/test/chunking-form/samples/namespace-reexports/_expected/es/generated-index.js
index aa297829f3f..8909c925361 100644
--- a/test/chunking-form/samples/namespace-reexports/_expected/es/generated-index.js
+++ b/test/chunking-form/samples/namespace-reexports/_expected/es/generated-index.js
@@ -6,6 +6,7 @@ var hsl2hsv = 'asdf';
 console.log(hsl2hsv);
 
 var lib = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	hsl2hsv: hsl2hsv$1
 });
 
diff --git a/test/chunking-form/samples/namespace-reexports/_expected/system/generated-index.js b/test/chunking-form/samples/namespace-reexports/_expected/system/generated-index.js
index c1bc5d3dfa9..69c57be6889 100644
--- a/test/chunking-form/samples/namespace-reexports/_expected/system/generated-index.js
+++ b/test/chunking-form/samples/namespace-reexports/_expected/system/generated-index.js
@@ -13,6 +13,7 @@ System.register(['./hsl2hsv.js'], function (exports) {
 			console.log(hsl2hsv);
 
 			var lib = /*#__PURE__*/Object.freeze({
+				__proto__: null,
 				hsl2hsv: hsl2hsv$1
 			});
 			exports('l', lib);
diff --git a/test/form/samples/compact/_expected/amd.js b/test/form/samples/compact/_expected/amd.js
index f4dcdb9033c..ae3955b3c27 100644
--- a/test/form/samples/compact/_expected/amd.js
+++ b/test/form/samples/compact/_expected/amd.js
@@ -1,4 +1,4 @@
-define(['external'],function(x){'use strict';x=x&&x.hasOwnProperty('default')?x['default']:x;var self=/*#__PURE__*/Object.freeze({[Symbol.toStringTag]:'Module',get default(){return foo}});console.log(self);
+define(['external'],function(x){'use strict';x=x&&x.hasOwnProperty('default')?x['default']:x;var self=/*#__PURE__*/Object.freeze({[Symbol.toStringTag]:'Module',__proto__:null,get default(){return foo}});console.log(self);
 function foo () {
 	console.log( x );
 }
diff --git a/test/form/samples/compact/_expected/cjs.js b/test/form/samples/compact/_expected/cjs.js
index 361c43c7205..0c18fd099f3 100644
--- a/test/form/samples/compact/_expected/cjs.js
+++ b/test/form/samples/compact/_expected/cjs.js
@@ -1,4 +1,4 @@
-'use strict';function _interopDefault(e){return(e&&(typeof e==='object')&&'default'in e)?e['default']:e}var x=_interopDefault(require('external'));var self=/*#__PURE__*/Object.freeze({[Symbol.toStringTag]:'Module',get default(){return foo}});console.log(self);
+'use strict';function _interopDefault(e){return(e&&(typeof e==='object')&&'default'in e)?e['default']:e}var x=_interopDefault(require('external'));var self=/*#__PURE__*/Object.freeze({[Symbol.toStringTag]:'Module',__proto__:null,get default(){return foo}});console.log(self);
 function foo () {
 	console.log( x );
 }
diff --git a/test/form/samples/compact/_expected/es.js b/test/form/samples/compact/_expected/es.js
index 2ade9a52f1f..8440fbc9991 100644
--- a/test/form/samples/compact/_expected/es.js
+++ b/test/form/samples/compact/_expected/es.js
@@ -1,4 +1,4 @@
-import x from'external';var self=/*#__PURE__*/Object.freeze({[Symbol.toStringTag]:'Module',get default(){return foo}});console.log(self);
+import x from'external';var self=/*#__PURE__*/Object.freeze({[Symbol.toStringTag]:'Module',__proto__:null,get default(){return foo}});console.log(self);
 function foo () {
 	console.log( x );
 }
diff --git a/test/form/samples/compact/_expected/iife.js b/test/form/samples/compact/_expected/iife.js
index 90d89ca7d8b..110ab76bfb1 100644
--- a/test/form/samples/compact/_expected/iife.js
+++ b/test/form/samples/compact/_expected/iife.js
@@ -1,4 +1,4 @@
-var foo=(function(x){'use strict';x=x&&x.hasOwnProperty('default')?x['default']:x;var self=/*#__PURE__*/Object.freeze({[Symbol.toStringTag]:'Module',get default(){return foo}});console.log(self);
+var foo=(function(x){'use strict';x=x&&x.hasOwnProperty('default')?x['default']:x;var self=/*#__PURE__*/Object.freeze({[Symbol.toStringTag]:'Module',__proto__:null,get default(){return foo}});console.log(self);
 function foo () {
 	console.log( x );
 }
diff --git a/test/form/samples/compact/_expected/system.js b/test/form/samples/compact/_expected/system.js
index e819d842949..42b5074a7cb 100644
--- a/test/form/samples/compact/_expected/system.js
+++ b/test/form/samples/compact/_expected/system.js
@@ -1,4 +1,4 @@
-System.register('foo',['external'],function(exports){'use strict';var x;return{setters:[function(module){x=module.default;}],execute:function(){exports('default',foo);var self=/*#__PURE__*/Object.freeze({[Symbol.toStringTag]:'Module',get default(){return foo}});console.log(self);
+System.register('foo',['external'],function(exports){'use strict';var x;return{setters:[function(module){x=module.default;}],execute:function(){exports('default',foo);var self=/*#__PURE__*/Object.freeze({[Symbol.toStringTag]:'Module',__proto__:null,get default(){return foo}});console.log(self);
 function foo () {
 	console.log( x );
 }
diff --git a/test/form/samples/compact/_expected/umd.js b/test/form/samples/compact/_expected/umd.js
index 443f7265209..8a112451052 100644
--- a/test/form/samples/compact/_expected/umd.js
+++ b/test/form/samples/compact/_expected/umd.js
@@ -1,4 +1,4 @@
-(function(g,f){typeof exports==='object'&&typeof module!=='undefined'?module.exports=f(require('external')):typeof define==='function'&&define.amd?define(['external'],f):(g=g||self,g.foo=f(g.x));}(this,function(x){'use strict';x=x&&x.hasOwnProperty('default')?x['default']:x;var self=/*#__PURE__*/Object.freeze({[Symbol.toStringTag]:'Module',get default(){return foo}});console.log(self);
+(function(g,f){typeof exports==='object'&&typeof module!=='undefined'?module.exports=f(require('external')):typeof define==='function'&&define.amd?define(['external'],f):(g=g||self,g.foo=f(g.x));}(this,function(x){'use strict';x=x&&x.hasOwnProperty('default')?x['default']:x;var self=/*#__PURE__*/Object.freeze({[Symbol.toStringTag]:'Module',__proto__:null,get default(){return foo}});console.log(self);
 function foo () {
 	console.log( x );
 }
diff --git a/test/form/samples/dynamic-import-inlining/_expected.js b/test/form/samples/dynamic-import-inlining/_expected.js
index 03ab247516e..ae434046e6c 100644
--- a/test/form/samples/dynamic-import-inlining/_expected.js
+++ b/test/form/samples/dynamic-import-inlining/_expected.js
@@ -4,6 +4,7 @@ Promise.resolve().then(function () { return foo$1; });
 const foo = 1;
 
 var foo$1 = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	foo: foo
 });
 
diff --git a/test/form/samples/freeze/_expected/amd.js b/test/form/samples/freeze/_expected/amd.js
index ee4280ef7f7..60c6a2683a6 100644
--- a/test/form/samples/freeze/_expected/amd.js
+++ b/test/form/samples/freeze/_expected/amd.js
@@ -4,6 +4,7 @@ define(['exports'], function (exports) { 'use strict';
 	const bar = 2;
 
 	var namespace = ({
+		__proto__: null,
 		foo: foo,
 		bar: bar
 	});
diff --git a/test/form/samples/freeze/_expected/cjs.js b/test/form/samples/freeze/_expected/cjs.js
index b9d3c67da24..c010fbc614a 100644
--- a/test/form/samples/freeze/_expected/cjs.js
+++ b/test/form/samples/freeze/_expected/cjs.js
@@ -6,6 +6,7 @@ const foo = 1;
 const bar = 2;
 
 var namespace = ({
+	__proto__: null,
 	foo: foo,
 	bar: bar
 });
diff --git a/test/form/samples/freeze/_expected/es.js b/test/form/samples/freeze/_expected/es.js
index 38e5ade2837..45de6b68c63 100644
--- a/test/form/samples/freeze/_expected/es.js
+++ b/test/form/samples/freeze/_expected/es.js
@@ -2,6 +2,7 @@ const foo = 1;
 const bar = 2;
 
 var namespace = ({
+	__proto__: null,
 	foo: foo,
 	bar: bar
 });
diff --git a/test/form/samples/freeze/_expected/iife.js b/test/form/samples/freeze/_expected/iife.js
index a86b90f7a80..1dc95266499 100644
--- a/test/form/samples/freeze/_expected/iife.js
+++ b/test/form/samples/freeze/_expected/iife.js
@@ -5,6 +5,7 @@ var myBundle = (function (exports) {
 	const bar = 2;
 
 	var namespace = ({
+		__proto__: null,
 		foo: foo,
 		bar: bar
 	});
diff --git a/test/form/samples/freeze/_expected/system.js b/test/form/samples/freeze/_expected/system.js
index 2e6511500f9..c331d83ceac 100644
--- a/test/form/samples/freeze/_expected/system.js
+++ b/test/form/samples/freeze/_expected/system.js
@@ -7,6 +7,7 @@ System.register('myBundle', [], function (exports) {
 			const bar = 2;
 
 			var namespace = ({
+				__proto__: null,
 				foo: foo,
 				bar: bar
 			});
diff --git a/test/form/samples/freeze/_expected/umd.js b/test/form/samples/freeze/_expected/umd.js
index bb1168a5a08..843b48f8c3f 100644
--- a/test/form/samples/freeze/_expected/umd.js
+++ b/test/form/samples/freeze/_expected/umd.js
@@ -8,6 +8,7 @@
 	const bar = 2;
 
 	var namespace = ({
+		__proto__: null,
 		foo: foo,
 		bar: bar
 	});
diff --git a/test/form/samples/namespace-object-import/_expected/amd.js b/test/form/samples/namespace-object-import/_expected/amd.js
index eea779d6e20..0e663d37254 100644
--- a/test/form/samples/namespace-object-import/_expected/amd.js
+++ b/test/form/samples/namespace-object-import/_expected/amd.js
@@ -3,6 +3,7 @@ define(function () { 'use strict';
 	var dep = "default";
 
 	var dep$1 = /*#__PURE__*/Object.freeze({
+		__proto__: null,
 		'default': dep
 	});
 
diff --git a/test/form/samples/namespace-object-import/_expected/cjs.js b/test/form/samples/namespace-object-import/_expected/cjs.js
index 2271b4c45d8..c27e146679f 100644
--- a/test/form/samples/namespace-object-import/_expected/cjs.js
+++ b/test/form/samples/namespace-object-import/_expected/cjs.js
@@ -3,6 +3,7 @@
 var dep = "default";
 
 var dep$1 = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	'default': dep
 });
 
diff --git a/test/form/samples/namespace-object-import/_expected/es.js b/test/form/samples/namespace-object-import/_expected/es.js
index 321ce0ebcbc..fc850f02f55 100644
--- a/test/form/samples/namespace-object-import/_expected/es.js
+++ b/test/form/samples/namespace-object-import/_expected/es.js
@@ -1,6 +1,7 @@
 var dep = "default";
 
 var dep$1 = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	'default': dep
 });
 
diff --git a/test/form/samples/namespace-object-import/_expected/iife.js b/test/form/samples/namespace-object-import/_expected/iife.js
index 8560919ed54..8048e57105b 100644
--- a/test/form/samples/namespace-object-import/_expected/iife.js
+++ b/test/form/samples/namespace-object-import/_expected/iife.js
@@ -4,6 +4,7 @@
 	var dep = "default";
 
 	var dep$1 = /*#__PURE__*/Object.freeze({
+		__proto__: null,
 		'default': dep
 	});
 
diff --git a/test/form/samples/namespace-object-import/_expected/system.js b/test/form/samples/namespace-object-import/_expected/system.js
index 16852da03f6..782f2137b93 100644
--- a/test/form/samples/namespace-object-import/_expected/system.js
+++ b/test/form/samples/namespace-object-import/_expected/system.js
@@ -6,6 +6,7 @@ System.register([], function () {
 			var dep = "default";
 
 			var dep$1 = /*#__PURE__*/Object.freeze({
+				__proto__: null,
 				'default': dep
 			});
 
diff --git a/test/form/samples/namespace-object-import/_expected/umd.js b/test/form/samples/namespace-object-import/_expected/umd.js
index 781060a2c00..175d0d9b1b3 100644
--- a/test/form/samples/namespace-object-import/_expected/umd.js
+++ b/test/form/samples/namespace-object-import/_expected/umd.js
@@ -6,6 +6,7 @@
 	var dep = "default";
 
 	var dep$1 = /*#__PURE__*/Object.freeze({
+		__proto__: null,
 		'default': dep
 	});
 
diff --git a/test/form/samples/namespace-self-import/_expected/amd.js b/test/form/samples/namespace-self-import/_expected/amd.js
index 50271286157..38976dc388e 100644
--- a/test/form/samples/namespace-self-import/_expected/amd.js
+++ b/test/form/samples/namespace-self-import/_expected/amd.js
@@ -1,6 +1,7 @@
 define(['exports'], function (exports) { 'use strict';
 
 	var self = /*#__PURE__*/Object.freeze({
+		__proto__: null,
 		get p () { return p; }
 	});
 
diff --git a/test/form/samples/namespace-self-import/_expected/cjs.js b/test/form/samples/namespace-self-import/_expected/cjs.js
index 0b8cb24fa60..286ebc2c57a 100644
--- a/test/form/samples/namespace-self-import/_expected/cjs.js
+++ b/test/form/samples/namespace-self-import/_expected/cjs.js
@@ -3,6 +3,7 @@
 Object.defineProperty(exports, '__esModule', { value: true });
 
 var self = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	get p () { return p; }
 });
 
diff --git a/test/form/samples/namespace-self-import/_expected/es.js b/test/form/samples/namespace-self-import/_expected/es.js
index af88cc937ef..b4e25aee52a 100644
--- a/test/form/samples/namespace-self-import/_expected/es.js
+++ b/test/form/samples/namespace-self-import/_expected/es.js
@@ -1,4 +1,5 @@
 var self = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	get p () { return p; }
 });
 
diff --git a/test/form/samples/namespace-self-import/_expected/iife.js b/test/form/samples/namespace-self-import/_expected/iife.js
index 5b03aaa5b6b..9eac34fd918 100644
--- a/test/form/samples/namespace-self-import/_expected/iife.js
+++ b/test/form/samples/namespace-self-import/_expected/iife.js
@@ -2,6 +2,7 @@ var iife = (function (exports) {
 	'use strict';
 
 	var self = /*#__PURE__*/Object.freeze({
+		__proto__: null,
 		get p () { return p; }
 	});
 
diff --git a/test/form/samples/namespace-self-import/_expected/system.js b/test/form/samples/namespace-self-import/_expected/system.js
index 730eabb5996..370359f60d3 100644
--- a/test/form/samples/namespace-self-import/_expected/system.js
+++ b/test/form/samples/namespace-self-import/_expected/system.js
@@ -4,6 +4,7 @@ System.register('iife', [], function (exports) {
 		execute: function () {
 
 			var self = /*#__PURE__*/Object.freeze({
+				__proto__: null,
 				get p () { return p; }
 			});
 
diff --git a/test/form/samples/namespace-self-import/_expected/umd.js b/test/form/samples/namespace-self-import/_expected/umd.js
index 611c0f7a26e..23766c5c4f8 100644
--- a/test/form/samples/namespace-self-import/_expected/umd.js
+++ b/test/form/samples/namespace-self-import/_expected/umd.js
@@ -5,6 +5,7 @@
 }(this, function (exports) { 'use strict';
 
 	var self = /*#__PURE__*/Object.freeze({
+		__proto__: null,
 		get p () { return p; }
 	});
 
diff --git a/test/form/samples/namespace-tostringtag/_expected/amd.js b/test/form/samples/namespace-tostringtag/_expected/amd.js
index 4f533907284..e6ddbfd62f1 100644
--- a/test/form/samples/namespace-tostringtag/_expected/amd.js
+++ b/test/form/samples/namespace-tostringtag/_expected/amd.js
@@ -2,6 +2,7 @@ define(['exports'], function (exports) { 'use strict';
 
 	var self = /*#__PURE__*/Object.freeze({
 		[Symbol.toStringTag]: 'Module',
+		__proto__: null,
 		get p () { return p; }
 	});
 
diff --git a/test/form/samples/namespace-tostringtag/_expected/cjs.js b/test/form/samples/namespace-tostringtag/_expected/cjs.js
index 29707aa7bf7..9eb8fe5b21f 100644
--- a/test/form/samples/namespace-tostringtag/_expected/cjs.js
+++ b/test/form/samples/namespace-tostringtag/_expected/cjs.js
@@ -4,6 +4,7 @@ Object.defineProperty(exports, '__esModule', { value: true });
 
 var self = /*#__PURE__*/Object.freeze({
 	[Symbol.toStringTag]: 'Module',
+	__proto__: null,
 	get p () { return p; }
 });
 
diff --git a/test/form/samples/namespace-tostringtag/_expected/es.js b/test/form/samples/namespace-tostringtag/_expected/es.js
index aeb84e06686..b5e71f3c02f 100644
--- a/test/form/samples/namespace-tostringtag/_expected/es.js
+++ b/test/form/samples/namespace-tostringtag/_expected/es.js
@@ -1,5 +1,6 @@
 var self = /*#__PURE__*/Object.freeze({
 	[Symbol.toStringTag]: 'Module',
+	__proto__: null,
 	get p () { return p; }
 });
 
diff --git a/test/form/samples/namespace-tostringtag/_expected/iife.js b/test/form/samples/namespace-tostringtag/_expected/iife.js
index c51559a5be6..e03dfc5a3f2 100644
--- a/test/form/samples/namespace-tostringtag/_expected/iife.js
+++ b/test/form/samples/namespace-tostringtag/_expected/iife.js
@@ -3,6 +3,7 @@ var iife = (function (exports) {
 
 	var self = /*#__PURE__*/Object.freeze({
 		[Symbol.toStringTag]: 'Module',
+		__proto__: null,
 		get p () { return p; }
 	});
 
diff --git a/test/form/samples/namespace-tostringtag/_expected/system.js b/test/form/samples/namespace-tostringtag/_expected/system.js
index 8dbbf4f6702..5e4bc576382 100644
--- a/test/form/samples/namespace-tostringtag/_expected/system.js
+++ b/test/form/samples/namespace-tostringtag/_expected/system.js
@@ -5,6 +5,7 @@ System.register('iife', [], function (exports) {
 
 			var self = /*#__PURE__*/Object.freeze({
 				[Symbol.toStringTag]: 'Module',
+				__proto__: null,
 				get p () { return p; }
 			});
 
diff --git a/test/form/samples/namespace-tostringtag/_expected/umd.js b/test/form/samples/namespace-tostringtag/_expected/umd.js
index e0c9dd8bc49..5b2d4399f88 100644
--- a/test/form/samples/namespace-tostringtag/_expected/umd.js
+++ b/test/form/samples/namespace-tostringtag/_expected/umd.js
@@ -6,6 +6,7 @@
 
 	var self = /*#__PURE__*/Object.freeze({
 		[Symbol.toStringTag]: 'Module',
+		__proto__: null,
 		get p () { return p; }
 	});
 
diff --git a/test/form/samples/namespaces-have-null-prototype/_config.js b/test/form/samples/namespaces-have-null-prototype/_config.js
new file mode 100644
index 00000000000..faa0ac1b8e7
--- /dev/null
+++ b/test/form/samples/namespaces-have-null-prototype/_config.js
@@ -0,0 +1,6 @@
+module.exports = {
+	description: 'creates namespaces with null prototypes',
+	options: {
+		output: { name: 'myBundle' }
+	}
+};
diff --git a/test/form/samples/namespaces-have-null-prototype/_expected/amd.js b/test/form/samples/namespaces-have-null-prototype/_expected/amd.js
new file mode 100644
index 00000000000..b53ccd4d76e
--- /dev/null
+++ b/test/form/samples/namespaces-have-null-prototype/_expected/amd.js
@@ -0,0 +1,22 @@
+define(['exports'], function (exports) { 'use strict';
+
+	const foo = 1;
+	const bar = 2;
+
+	var namespace = /*#__PURE__*/Object.freeze({
+		__proto__: null,
+		foo: foo,
+		bar: bar
+	});
+
+	console.log( Object.keys( namespace ) );
+
+	const a = 1;
+	const b = 2;
+
+	exports.a = a;
+	exports.b = b;
+
+	Object.defineProperty(exports, '__esModule', { value: true });
+
+});
diff --git a/test/form/samples/namespaces-have-null-prototype/_expected/cjs.js b/test/form/samples/namespaces-have-null-prototype/_expected/cjs.js
new file mode 100644
index 00000000000..445e1b89d69
--- /dev/null
+++ b/test/form/samples/namespaces-have-null-prototype/_expected/cjs.js
@@ -0,0 +1,20 @@
+'use strict';
+
+Object.defineProperty(exports, '__esModule', { value: true });
+
+const foo = 1;
+const bar = 2;
+
+var namespace = /*#__PURE__*/Object.freeze({
+	__proto__: null,
+	foo: foo,
+	bar: bar
+});
+
+console.log( Object.keys( namespace ) );
+
+const a = 1;
+const b = 2;
+
+exports.a = a;
+exports.b = b;
diff --git a/test/form/samples/namespaces-have-null-prototype/_expected/es.js b/test/form/samples/namespaces-have-null-prototype/_expected/es.js
new file mode 100644
index 00000000000..6f660a34a59
--- /dev/null
+++ b/test/form/samples/namespaces-have-null-prototype/_expected/es.js
@@ -0,0 +1,15 @@
+const foo = 1;
+const bar = 2;
+
+var namespace = /*#__PURE__*/Object.freeze({
+	__proto__: null,
+	foo: foo,
+	bar: bar
+});
+
+console.log( Object.keys( namespace ) );
+
+const a = 1;
+const b = 2;
+
+export { a, b };
diff --git a/test/form/samples/namespaces-have-null-prototype/_expected/iife.js b/test/form/samples/namespaces-have-null-prototype/_expected/iife.js
new file mode 100644
index 00000000000..e31bea3b476
--- /dev/null
+++ b/test/form/samples/namespaces-have-null-prototype/_expected/iife.js
@@ -0,0 +1,23 @@
+var myBundle = (function (exports) {
+	'use strict';
+
+	const foo = 1;
+	const bar = 2;
+
+	var namespace = /*#__PURE__*/Object.freeze({
+		__proto__: null,
+		foo: foo,
+		bar: bar
+	});
+
+	console.log( Object.keys( namespace ) );
+
+	const a = 1;
+	const b = 2;
+
+	exports.a = a;
+	exports.b = b;
+
+	return exports;
+
+}({}));
diff --git a/test/form/samples/namespaces-have-null-prototype/_expected/system.js b/test/form/samples/namespaces-have-null-prototype/_expected/system.js
new file mode 100644
index 00000000000..258f8497c83
--- /dev/null
+++ b/test/form/samples/namespaces-have-null-prototype/_expected/system.js
@@ -0,0 +1,22 @@
+System.register('myBundle', [], function (exports) {
+	'use strict';
+	return {
+		execute: function () {
+
+			const foo = 1;
+			const bar = 2;
+
+			var namespace = /*#__PURE__*/Object.freeze({
+				__proto__: null,
+				foo: foo,
+				bar: bar
+			});
+
+			console.log( Object.keys( namespace ) );
+
+			const a = exports('a', 1);
+			const b = exports('b', 2);
+
+		}
+	};
+});
diff --git a/test/form/samples/namespaces-have-null-prototype/_expected/umd.js b/test/form/samples/namespaces-have-null-prototype/_expected/umd.js
new file mode 100644
index 00000000000..5f67bceb3b9
--- /dev/null
+++ b/test/form/samples/namespaces-have-null-prototype/_expected/umd.js
@@ -0,0 +1,26 @@
+(function (global, factory) {
+	typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
+	typeof define === 'function' && define.amd ? define(['exports'], factory) :
+	(global = global || self, factory(global.myBundle = {}));
+}(this, function (exports) { 'use strict';
+
+	const foo = 1;
+	const bar = 2;
+
+	var namespace = /*#__PURE__*/Object.freeze({
+		__proto__: null,
+		foo: foo,
+		bar: bar
+	});
+
+	console.log( Object.keys( namespace ) );
+
+	const a = 1;
+	const b = 2;
+
+	exports.a = a;
+	exports.b = b;
+
+	Object.defineProperty(exports, '__esModule', { value: true });
+
+}));
diff --git a/test/form/samples/namespaces-have-null-prototype/main.js b/test/form/samples/namespaces-have-null-prototype/main.js
new file mode 100644
index 00000000000..d434187c18c
--- /dev/null
+++ b/test/form/samples/namespaces-have-null-prototype/main.js
@@ -0,0 +1,6 @@
+import * as namespace from './namespace.js';
+
+console.log( Object.keys( namespace ) );
+
+export const a = 1;
+export const b = 2;
diff --git a/test/form/samples/namespaces-have-null-prototype/namespace.js b/test/form/samples/namespaces-have-null-prototype/namespace.js
new file mode 100644
index 00000000000..7f502126131
--- /dev/null
+++ b/test/form/samples/namespaces-have-null-prototype/namespace.js
@@ -0,0 +1,2 @@
+export const foo = 1;
+export const bar = 2;
\ No newline at end of file
diff --git a/test/form/samples/prefer-const/_expected/amd.js b/test/form/samples/prefer-const/_expected/amd.js
index 540dfd929bd..0f423ee98cb 100644
--- a/test/form/samples/prefer-const/_expected/amd.js
+++ b/test/form/samples/prefer-const/_expected/amd.js
@@ -4,6 +4,7 @@ define(['other'], function (other) { 'use strict';
 	const b = 2;
 
 	const namespace = /*#__PURE__*/Object.freeze({
+		__proto__: null,
 		a: a,
 		b: b
 	});
diff --git a/test/form/samples/prefer-const/_expected/cjs.js b/test/form/samples/prefer-const/_expected/cjs.js
index 92bd84e15e5..01aa90d1548 100644
--- a/test/form/samples/prefer-const/_expected/cjs.js
+++ b/test/form/samples/prefer-const/_expected/cjs.js
@@ -6,6 +6,7 @@ const a = 1;
 const b = 2;
 
 const namespace = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	a: a,
 	b: b
 });
diff --git a/test/form/samples/prefer-const/_expected/es.js b/test/form/samples/prefer-const/_expected/es.js
index d6a49579dcc..24735286aa8 100644
--- a/test/form/samples/prefer-const/_expected/es.js
+++ b/test/form/samples/prefer-const/_expected/es.js
@@ -4,6 +4,7 @@ const a = 1;
 const b = 2;
 
 const namespace = /*#__PURE__*/Object.freeze({
+	__proto__: null,
 	a: a,
 	b: b
 });
diff --git a/test/form/samples/prefer-const/_expected/iife.js b/test/form/samples/prefer-const/_expected/iife.js
index e40ca88e3de..72652cb62ef 100644
--- a/test/form/samples/prefer-const/_expected/iife.js
+++ b/test/form/samples/prefer-const/_expected/iife.js
@@ -5,6 +5,7 @@ const myBundle = (function (other) {
 	const b = 2;
 
 	const namespace = /*#__PURE__*/Object.freeze({
+		__proto__: null,
 		a: a,
 		b: b
 	});
diff --git a/test/form/samples/prefer-const/_expected/system.js b/test/form/samples/prefer-const/_expected/system.js
index c0f85eb7134..a0599b20df8 100644
--- a/test/form/samples/prefer-const/_expected/system.js
+++ b/test/form/samples/prefer-const/_expected/system.js
@@ -11,6 +11,7 @@ System.register('myBundle', ['other'], function (exports) {
 			const b = 2;
 
 			const namespace = /*#__PURE__*/Object.freeze({
+				__proto__: null,
 				a: a,
 				b: b
 			});
diff --git a/test/form/samples/prefer-const/_expected/umd.js b/test/form/samples/prefer-const/_expected/umd.js
index 121c9f6c245..36f9cec35ce 100644
--- a/test/form/samples/prefer-const/_expected/umd.js
+++ b/test/form/samples/prefer-const/_expected/umd.js
@@ -8,6 +8,7 @@
 	const b = 2;
 
 	const namespace = /*#__PURE__*/Object.freeze({
+		__proto__: null,
 		a: a,
 		b: b
 	});
diff --git a/test/function/samples/namespace-tostring/main.js b/test/function/samples/namespace-tostring/main.js
index dd991f848c9..13e195fd6c1 100644
--- a/test/function/samples/namespace-tostring/main.js
+++ b/test/function/samples/namespace-tostring/main.js
@@ -1,4 +1,4 @@
 import * as foo from './foo';
 
-assert.equal("" + foo, "[object Module]");
+assert.equal(Object.prototype.toString.call(foo), "[object Module]");
 assert.equal(foo.bar, 42);
diff --git a/test/function/samples/namespaces-have-null-prototype/_config.js b/test/function/samples/namespaces-have-null-prototype/_config.js
new file mode 100644
index 00000000000..d64597e0b9f
--- /dev/null
+++ b/test/function/samples/namespaces-have-null-prototype/_config.js
@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'creates namespaces with null prototypes'
+};
diff --git a/test/function/samples/namespaces-have-null-prototype/main.js b/test/function/samples/namespaces-have-null-prototype/main.js
new file mode 100644
index 00000000000..51b5a680979
--- /dev/null
+++ b/test/function/samples/namespaces-have-null-prototype/main.js
@@ -0,0 +1,3 @@
+import * as ns from './mod';
+
+assert.equal( Object.getPrototypeOf(ns), null );
diff --git a/test/function/samples/namespaces-have-null-prototype/mod.js b/test/function/samples/namespaces-have-null-prototype/mod.js
new file mode 100644
index 00000000000..0b0c3304ff3
--- /dev/null
+++ b/test/function/samples/namespaces-have-null-prototype/mod.js
@@ -0,0 +1,2 @@
+export var a = 1;
+export var b = 2;
diff --git a/test/function/samples/transparent-dynamic-inlining/foo.js b/test/function/samples/transparent-dynamic-inlining/foo.js
index 96b14ac739a..61a9615ee29 100644
--- a/test/function/samples/transparent-dynamic-inlining/foo.js
+++ b/test/function/samples/transparent-dynamic-inlining/foo.js
@@ -1,4 +1,7 @@
 export var x = 42;
 import('./main').then(x => {
-	assert.deepStrictEqual(x, { y: 42 });
+	const expected = { y: 42 };
+	Object.setPrototypeOf(expected, null);
+
+	assert.deepStrictEqual(x, expected);
 });