diff --git a/package-lock.json b/package-lock.json
index 399394a5..376124da 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -11771,6 +11771,15 @@
 				}
 			}
 		},
+		"rollup-plugin-polyfill": {
+			"version": "3.0.0",
+			"resolved": "https://registry.npmjs.org/rollup-plugin-polyfill/-/rollup-plugin-polyfill-3.0.0.tgz",
+			"integrity": "sha512-LfJ1OR/wJrJdNDVNrdhVm7CgENfaNoQlFYMaQ0vlQH3zO+BMVrBMWDX9k6HVcr9gHsKbthrkiBzWRfFU9fr0hQ==",
+			"dev": true,
+			"requires": {
+				"magic-string": "^0.25.3"
+			}
+		},
 		"rollup-plugin-sourcemaps": {
 			"version": "0.4.2",
 			"resolved": "https://registry.npmjs.org/rollup-plugin-sourcemaps/-/rollup-plugin-sourcemaps-0.4.2.tgz",
diff --git a/package.json b/package.json
index 5d3b2c30..098c182d 100644
--- a/package.json
+++ b/package.json
@@ -28,13 +28,14 @@
     "rollup-plugin-commonjs": "^10.0.1",
     "rollup-plugin-eslint": "^7.0.0",
     "rollup-plugin-node-resolve": "^5.2.0",
+    "rollup-plugin-polyfill": "^3.0.0",
     "rollup-plugin-sourcemaps": "^0.4.2",
     "rollup-plugin-terser": "^5.1.1",
     "sinon": "^7.3.2"
   },
   "engines": {
     "npm": ">=4.0.0",
-    "node": ">=6.0.0"
+    "node": ">=8.0.0"
   },
   "scripts": {
     "postinstall": "lerna bootstrap --hoist --nohoist=core-js --no-ci",
diff --git a/packages/imask/.babelrc.js b/packages/imask/.babelrc.js
index 5c2079ce..bf226ddf 100644
--- a/packages/imask/.babelrc.js
+++ b/packages/imask/.babelrc.js
@@ -1,5 +1,4 @@
 const presetOptions = {
-  modules: false,
   useBuiltIns: 'entry',
   corejs: '3',
 };
diff --git a/packages/imask/package.json b/packages/imask/package.json
index 285bccfa..738d26f1 100644
--- a/packages/imask/package.json
+++ b/packages/imask/package.json
@@ -7,6 +7,7 @@
   "homepage": "https://imask.js.org/",
   "description": "vanilla javascript input mask",
   "main": "dist/imask.js",
+  "module": "dist/imask.esm.js",
   "repository": "https://github.com/uNmAnNeR/imaskjs",
   "types": "index.d.ts",
   "engines": {
@@ -16,13 +17,10 @@
     "test": "cross-env NODE_ENV=test nyc mocha --exit --recursive",
     "pretest": "flow check",
     "watch": "rollup -c -w",
-    "build": "npm run build:dev && npm run build:prod",
-    "build:dev": "npm run build:dev:es && npm run build:dev:umd",
-    "build:prod": "npm run build:prod:es && npm run build:prod:umd",
-    "build:dev:es": "cross-env BABEL_ENV=es rollup -c",
-    "build:dev:umd": "rollup -c",
-    "build:prod:es": "cross-env NODE_ENV=production BABEL_ENV=es rollup -c",
-    "build:prod:umd": "cross-env NODE_ENV=production rollup -c",
+    "build": "npm run build:umd && npm run build:es && npm run build:esm",
+    "build:umd": "rollup -c",
+    "build:es": "cross-env BABEL_ENV=es rollup -c",
+    "build:esm": "cross-env BABEL_ENV=esm rollup -c",
     "flow": "flow",
     "coveralls": "nyc report --reporter=text-lcov | coveralls"
   },
diff --git a/packages/imask/rollup.config.js b/packages/imask/rollup.config.js
index 7febb035..3afb9c05 100644
--- a/packages/imask/rollup.config.js
+++ b/packages/imask/rollup.config.js
@@ -3,24 +3,19 @@ import { terser } from 'rollup-plugin-terser';
 import { eslint } from 'rollup-plugin-eslint';
 import resolve from 'rollup-plugin-node-resolve';
 import commonjs from 'rollup-plugin-commonjs';
+import polyfill from 'rollup-plugin-polyfill';
 
 
-const isProd = process.env.NODE_ENV === 'production';
 const format = process.env.BABEL_ENV || 'umd';
 
-const isES = format === 'es';
-const file = 'dist/imask' +
-  (format !== 'umd' ? '.' + format : '') +
-  (isProd ? '.min' : '') +
-  '.js';
+const isES = format.indexOf('es') === 0;
+const basePath = 'dist/imask' + (format !== 'umd' ? '.' + format : '');
 
-const input = isES ? 'src/imask.js' : 'src/imask.shim.js';
 
-
-export default {
-  input,
+export default [false, true].map(min => ({
+  input: 'src/imask.js',
   output: {
-    file,
+    file: `${basePath}${min ? '.min' : ''}.js`,
     format,
     name: 'IMask',
     sourcemap: true,
@@ -30,6 +25,7 @@ export default {
     resolve(),
     babel(),
     !isES && commonjs(),
-    isProd && terser()
-  ]
-}
+    !isES && polyfill(['./polyfills.js']),
+    min && terser(),
+  ],
+}));
diff --git a/packages/imask/src/imask.shim.js b/packages/imask/src/imask.shim.js
deleted file mode 100644
index b53b8e87..00000000
--- a/packages/imask/src/imask.shim.js
+++ /dev/null
@@ -1,3 +0,0 @@
-import './polyfills.js';
-import IMask from './imask.js';
-export default IMask;