diff --git a/packages/commonjs/src/helpers.js b/packages/commonjs/src/helpers.js
index e75841556..be25fbbd5 100644
--- a/packages/commonjs/src/helpers.js
+++ b/packages/commonjs/src/helpers.js
@@ -35,6 +35,7 @@ export function getDefaultExportFromNamespaceIfNotNamed (n) {
 }
 
 export function getAugmentedNamespace(n) {
+  if (n.__esModule) return n;
   var f = n.default;
 	if (typeof f == "function") {
 		var a = function a () {
diff --git a/packages/commonjs/test/snapshots/function.js.md b/packages/commonjs/test/snapshots/function.js.md
index e01a4cfeb..f3d4c2c0f 100644
--- a/packages/commonjs/test/snapshots/function.js.md
+++ b/packages/commonjs/test/snapshots/function.js.md
@@ -3491,6 +3491,7 @@ Generated by [AVA](https://avajs.dev).
       var externalEsmDefault__namespace = /*#__PURE__*/_interopNamespaceCompat(externalEsmDefault);␊
       ␊
       function getAugmentedNamespace(n) {␊
+        if (n.__esModule) return n;␊
         var f = n.default;␊
       	if (typeof f == "function") {␊
       		var a = function a () {␊
@@ -3577,6 +3578,7 @@ Generated by [AVA](https://avajs.dev).
       var externalEsmDefault__namespace = /*#__PURE__*/_interopNamespaceCompat(externalEsmDefault);␊
       ␊
       function getAugmentedNamespace(n) {␊
+        if (n.__esModule) return n;␊
         var f = n.default;␊
       	if (typeof f == "function") {␊
       		var a = function a () {␊
@@ -3657,6 +3659,7 @@ Generated by [AVA](https://avajs.dev).
       var externalEsmDefault__namespace = /*#__PURE__*/_interopNamespaceCompat(externalEsmDefault);␊
       ␊
       function getAugmentedNamespace(n) {␊
+        if (n.__esModule) return n;␊
         var f = n.default;␊
       	if (typeof f == "function") {␊
       		var a = function a () {␊
@@ -3750,6 +3753,7 @@ Generated by [AVA](https://avajs.dev).
       'main.js': `'use strict';␊
       ␊
       function getAugmentedNamespace(n) {␊
+        if (n.__esModule) return n;␊
         var f = n.default;␊
       	if (typeof f == "function") {␊
       		var a = function a () {␊
@@ -3957,6 +3961,7 @@ Generated by [AVA](https://avajs.dev).
       'main.js': `'use strict';␊
       ␊
       function getAugmentedNamespace(n) {␊
+        if (n.__esModule) return n;␊
         var f = n.default;␊
       	if (typeof f == "function") {␊
       		var a = function a () {␊
@@ -4187,6 +4192,7 @@ Generated by [AVA](https://avajs.dev).
       var externalEsmDefault__namespace = /*#__PURE__*/_interopNamespaceCompat(externalEsmDefault);␊
       ␊
       function getAugmentedNamespace(n) {␊
+        if (n.__esModule) return n;␊
         var f = n.default;␊
       	if (typeof f == "function") {␊
       		var a = function a () {␊
@@ -4289,6 +4295,7 @@ Generated by [AVA](https://avajs.dev).
       'main.js': `'use strict';␊
       ␊
       function getAugmentedNamespace(n) {␊
+        if (n.__esModule) return n;␊
         var f = n.default;␊
       	if (typeof f == "function") {␊
       		var a = function a () {␊
@@ -4482,6 +4489,7 @@ Generated by [AVA](https://avajs.dev).
       }␊
       ␊
       function getAugmentedNamespace(n) {␊
+        if (n.__esModule) return n;␊
         var f = n.default;␊
       	if (typeof f == "function") {␊
       		var a = function a () {␊
@@ -4760,6 +4768,7 @@ Generated by [AVA](https://avajs.dev).
       var externalEsmDefault__namespace = /*#__PURE__*/_interopNamespaceCompat(externalEsmDefault);␊
       ␊
       function getAugmentedNamespace(n) {␊
+        if (n.__esModule) return n;␊
         var f = n.default;␊
       	if (typeof f == "function") {␊
       		var a = function a () {␊
@@ -4854,6 +4863,7 @@ Generated by [AVA](https://avajs.dev).
       'main.js': `'use strict';␊
       ␊
       function getAugmentedNamespace(n) {␊
+        if (n.__esModule) return n;␊
         var f = n.default;␊
       	if (typeof f == "function") {␊
       		var a = function a () {␊
@@ -6163,6 +6173,7 @@ Generated by [AVA](https://avajs.dev).
       'main.js': `'use strict';␊
       ␊
       function getAugmentedNamespace(n) {␊
+        if (n.__esModule) return n;␊
         var f = n.default;␊
       	if (typeof f == "function") {␊
       		var a = function a () {␊
@@ -6214,6 +6225,7 @@ Generated by [AVA](https://avajs.dev).
       'main.js': `'use strict';␊
       ␊
       function getAugmentedNamespace(n) {␊
+        if (n.__esModule) return n;␊
         var f = n.default;␊
       	if (typeof f == "function") {␊
       		var a = function a () {␊
@@ -7167,6 +7179,7 @@ Generated by [AVA](https://avajs.dev).
       'main.js': `'use strict';␊
       ␊
       function getAugmentedNamespace(n) {␊
+        if (n.__esModule) return n;␊
         var f = n.default;␊
       	if (typeof f == "function") {␊
       		var a = function a () {␊
diff --git a/packages/commonjs/test/snapshots/function.js.snap b/packages/commonjs/test/snapshots/function.js.snap
index c004e1f6b..afa7ef9d8 100644
Binary files a/packages/commonjs/test/snapshots/function.js.snap and b/packages/commonjs/test/snapshots/function.js.snap differ
diff --git a/packages/commonjs/test/snapshots/test.js.md b/packages/commonjs/test/snapshots/test.js.md
index 706386cd0..0dab2cd1b 100644
--- a/packages/commonjs/test/snapshots/test.js.md
+++ b/packages/commonjs/test/snapshots/test.js.md
@@ -42,6 +42,7 @@ Generated by [AVA](https://avajs.dev).
     }␊
     ␊
     function getAugmentedNamespace(n) {␊
+      if (n.__esModule) return n;␊
       var f = n.default;␊
     	if (typeof f == "function") {␊
     		var a = function a () {␊
@@ -199,6 +200,7 @@ Generated by [AVA](https://avajs.dev).
     `'use strict';␊
     ␊
     function getAugmentedNamespace(n) {␊
+      if (n.__esModule) return n;␊
       var f = n.default;␊
     	if (typeof f == "function") {␊
     		var a = function a () {␊
@@ -279,6 +281,7 @@ Generated by [AVA](https://avajs.dev).
     `'use strict';␊
     ␊
     function getAugmentedNamespace(n) {␊
+      if (n.__esModule) return n;␊
       var f = n.default;␊
     	if (typeof f == "function") {␊
     		var a = function a () {␊
diff --git a/packages/commonjs/test/snapshots/test.js.snap b/packages/commonjs/test/snapshots/test.js.snap
index 850d912ad..c7ff770ef 100644
Binary files a/packages/commonjs/test/snapshots/test.js.snap and b/packages/commonjs/test/snapshots/test.js.snap differ
diff --git a/packages/commonjs/test/test.js b/packages/commonjs/test/test.js
index 44234545b..d09573739 100644
--- a/packages/commonjs/test/test.js
+++ b/packages/commonjs/test/test.js
@@ -2,6 +2,7 @@
 
 const os = require('os');
 const path = require('path');
+const vm = require('vm');
 
 const { nodeResolve } = require('@rollup/plugin-node-resolve');
 const test = require('ava');
@@ -598,6 +599,33 @@ test('produces optimized code when importing esm without a default export', asyn
   t.snapshot(await getCodeFromBundle(bundle));
 });
 
+test('produces working code when importing esm with __esModule property set', async (t) => {
+  const bundle = await rollup({
+    input: 'main.js',
+    plugins: [
+      commonjs(),
+      loader({
+        'main.js': 'const {y} = require("withEsModule.js"); module.exports = y + 1;',
+        'withEsModule.js': 'export const y = 1; export const __esModule=true;'
+      })
+    ]
+  });
+  const name = 'bundleExecutionResult';
+  const code = await getCodeFromBundle(bundle, {
+    format: 'iife',
+    name
+  });
+
+  const context = {};
+  vm.createContext(context);
+  vm.runInContext(code, context);
+  t.is(
+    context[name],
+    2,
+    `Expected to get 2, but got ${context[name]} after running bundled code: \n${code}`
+  );
+});
+
 test('handles array destructuring assignment', async (t) => {
   const bundle = await rollup({
     input: 'fixtures/samples/array-destructuring-assignment/main.js',