diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ca9b426..64e0392 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -13,4 +13,5 @@ jobs:
           node-version: 14
       - run: npm ci
       - run: npm run compile
+      - run: npm run compile:esm
       - run: npm test
diff --git a/package.json b/package.json
index e6c32f0..ff7b21b 100644
--- a/package.json
+++ b/package.json
@@ -6,6 +6,7 @@
     "name": "Microsoft Corporation"
   },
   "main": "./release/main.js",
+  "module": "./release/esm/main.js",
   "typings": "./release/main.d.ts",
   "repository": {
     "type": "git",
@@ -18,13 +19,14 @@
   "scripts": {
     "watch": "tsc --watch",
     "compile": "tsc",
+    "compile:esm": "tsc -b ./tsconfig.esm.json",
     "test": "mocha --ui=tdd ./out/tests/all.test.js",
     "benchmark": "node benchmark/benchmark.js",
     "inspect": "node out/tests/inspect.js",
     "tmconvert": "node scripts/tmconvert.js",
     "version": "npm run compile && npm run test",
     "postversion": "git push && git push --tags",
-    "prepublishOnly": "tsc && webpack --progress",
+    "prepublishOnly": "tsc && tsc -b ./tsconfig.esm.json && webpack --progress",
     "bundle": "webpack"
   },
   "devDependencies": {
diff --git a/src/diffStateStacks.ts b/src/diffStateStacks.ts
index d2528e5..5a18e31 100644
--- a/src/diffStateStacks.ts
+++ b/src/diffStateStacks.ts
@@ -2,7 +2,7 @@
  * Copyright (C) Microsoft Corporation. All rights reserved.
  *--------------------------------------------------------*/
 
-import { StateStackImpl, StateStackFrame } from "./grammar";
+import { StateStackImpl, StateStackFrame } from "./grammar/index";
 import { StateStack } from "./main";
 
 export function diffStateStacksRefEq(first: StateStack, second: StateStack): StackDiff {
diff --git a/src/main.ts b/src/main.ts
index b79dd99..de9d92f 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -2,7 +2,7 @@
  * Copyright (C) Microsoft Corporation. All rights reserved.
  *--------------------------------------------------------*/
 
-import { BalancedBracketSelectors, StateStackImpl } from './grammar';
+import { BalancedBracketSelectors, StateStackImpl } from './grammar/index';
 import * as grammarReader from './parseRawGrammar';
 import { IOnigLib } from './onigLib';
 import { IRawGrammar } from './rawGrammar';
diff --git a/src/registry.ts b/src/registry.ts
index 600608c..9e60a6d 100644
--- a/src/registry.ts
+++ b/src/registry.ts
@@ -2,7 +2,7 @@
  * Copyright (C) Microsoft Corporation. All rights reserved.
  *--------------------------------------------------------*/
 
-import { BalancedBracketSelectors, createGrammar, Grammar, IGrammarRepository, IThemeProvider, AttributedScopeStack } from './grammar';
+import { BalancedBracketSelectors, createGrammar, Grammar, IGrammarRepository, IThemeProvider, AttributedScopeStack } from './grammar/index';
 import { IRawGrammar } from './rawGrammar';
 import { IGrammar, IEmbeddedLanguagesMap, ITokenTypeMap } from './main';
 import { ScopeStack, Theme, StyleAttributes, ThemeTrieElementRule, ScopeName } from './theme';
diff --git a/src/tests/inspect.ts b/src/tests/inspect.ts
index 3a1a565..85df15a 100644
--- a/src/tests/inspect.ts
+++ b/src/tests/inspect.ts
@@ -4,7 +4,7 @@
 
 import * as fs from 'fs';
 import { Registry, IGrammar, parseRawGrammar } from '../main';
-import { StateStackImpl as StackElementImpl, Grammar as GrammarImpl } from '../grammar';
+import { StateStackImpl as StackElementImpl, Grammar as GrammarImpl } from '../grammar/index';
 import * as debug from '../debug';
 import { getOniguruma } from './onigLibs';
 
diff --git a/tsconfig.esm.json b/tsconfig.esm.json
new file mode 100644
index 0000000..756bbf8
--- /dev/null
+++ b/tsconfig.esm.json
@@ -0,0 +1,8 @@
+{
+	"extends": "./tsconfig.json",
+	"compilerOptions": {
+		"module": "ES2020",
+		"outDir": "release/esm",
+		"sourceMap": false
+	}
+}