diff --git a/.gitignore b/.gitignore
index c6d0d10..3bd6c94 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,7 @@
-/node_modules
-/index.js
+/cjs
+/esm
 /index.d.ts
+/index.js
+/node_modules
 /test.js
+/umd
diff --git a/README.md b/README.md
index 1f2c2c0..a823fc0 100644
--- a/README.md
+++ b/README.md
@@ -12,6 +12,7 @@
 ## Features
 
 - Flow and TypeScript declarations included.
+- CommonJS, UMD and ESM modules provided.
 - Zero dependencies.
 
 ## Installation
diff --git a/package.json b/package.json
index a486d1f..b8a2f8f 100644
--- a/package.json
+++ b/package.json
@@ -11,19 +11,25 @@
     "intersect",
     "subset"
   ],
-  "main": "index.js",
+  "main": "cjs/index.js",
   "author": "Haydn Ewers",
   "license": "MIT",
   "private": false,
   "scripts": {
-    "build": "tsc index.ts --downlevelIteration --lib ES2015 -d",
+    "build": "yarn build:declaration && yarn build:cjs && yarn build:umd && yarn build:esm",
+    "build:declaration": "tsc index.ts --downlevelIteration --declaration --emitDeclarationOnly",
+    "build:cjs": "tsc index.ts --downlevelIteration --target ES2015 --module CommonJS --outDir cjs",
+    "build:umd": "tsc index.ts --downlevelIteration --target ES2015 --module UMD --outDir umd",
+    "build:esm": "tsc index.ts --target ESNext --module ESNext --outDir esm",
     "test": "tsc test.ts --downlevelIteration --lib ES2015 && node test.js",
     "release": "np"
   },
   "files": [
     "index.d.ts",
     "index.js.flow",
-    "index.js",
+    "cjs/index.js",
+    "umd/index.js",
+    "esm/index.js",
     "LICENSE",
     "README.md"
   ],
diff --git a/test.ts b/test.ts
index 3ecc8b0..833e858 100644
--- a/test.ts
+++ b/test.ts
@@ -10,7 +10,7 @@ import {
   strictSubset,
   superset,
   strictSuperset
-} from "./";
+} from "./index";
 
 assert.deepEqual(set(), new Set());