diff --git a/src/index.js b/src/index.js
index dfb566329..97cca7d69 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,3 +1,10 @@
-const VirtualMachine = require('./virtual-machine');
+import VirtualMachine from './virtual-machine.js';
 
-module.exports = VirtualMachine;
+import ArgumentType from './extension-support/argument-type.js';
+import BlockType from './extension-support/block-type.js';
+
+export default VirtualMachine;
+export {
+    ArgumentType,
+    BlockType
+};
diff --git a/src/virtual-machine.js b/src/virtual-machine.js
index 64ad7934f..750d76feb 100644
--- a/src/virtual-machine.js
+++ b/src/virtual-machine.js
@@ -1,28 +1,30 @@
+import EventEmitter from 'events';
+import JSZip from 'jszip';
+import {Buffer} from 'buffer';
+import centralDispatch from './dispatch/central-dispatch.js';
+import ExtensionManager from './extension-support/extension-manager.js';
+import log from './util/log.js';
+import MathUtil from './util/math-util.js';
+import Runtime from './engine/runtime.js';
+import StringUtil from './util/string-util.js';
+import * as formatMessage from 'format-message';
+import Variable from './engine/variable.js';
+import newBlockIds from './util/new-block-ids.js';
+import {loadCostume} from './import/load-costume.js';
+import {loadSound} from './import/load-sound.js';
+import {serializeSounds, serializeCostumes} from './serialization/serialize-assets.js';
+import 'canvas-toBlob';
+import validate from 'scratch-parser';
+import * as scratchSb1Converter from 'scratch-sb1-converter';
+import sb3 from './serialization/sb3.js';
+import sb2 from './serialization/sb2.js';
+
 let _TextEncoder;
 if (typeof TextEncoder === 'undefined') {
     _TextEncoder = require('text-encoding').TextEncoder;
 } else {
     _TextEncoder = TextEncoder;
 }
-const EventEmitter = require('events');
-const JSZip = require('jszip');
-
-const Buffer = require('buffer').Buffer;
-const centralDispatch = require('./dispatch/central-dispatch');
-const ExtensionManager = require('./extension-support/extension-manager');
-const log = require('./util/log');
-const MathUtil = require('./util/math-util');
-const Runtime = require('./engine/runtime');
-const StringUtil = require('./util/string-util');
-const formatMessage = require('format-message');
-
-const Variable = require('./engine/variable');
-const newBlockIds = require('./util/new-block-ids');
-
-const {loadCostume} = require('./import/load-costume.js');
-const {loadSound} = require('./import/load-sound.js');
-const {serializeSounds, serializeCostumes} = require('./serialization/serialize-assets');
-require('canvas-toBlob');
 
 const RESERVED_NAMES = ['_mouse_', '_stage_', '_edge_', '_myself_', '_random_'];
 
@@ -317,7 +319,6 @@ class VirtualMachine extends EventEmitter {
         }
 
         const validationPromise = new Promise((resolve, reject) => {
-            const validate = require('scratch-parser');
             // The second argument of false below indicates to the validator that the
             // input should be parsed/validated as an entire project (and not a single sprite)
             validate(input, false, (error, res) => {
@@ -326,7 +327,7 @@ class VirtualMachine extends EventEmitter {
             });
         })
             .catch(error => {
-                const {SB1File, ValidationError} = require('scratch-sb1-converter');
+                const {SB1File, ValidationError} = scratchSb1Converter;
 
                 try {
                     const sb1 = new SB1File(input);
@@ -462,7 +463,6 @@ class VirtualMachine extends EventEmitter {
      * @return {string} Serialized state of the runtime.
      */
     toJSON (optTargetId) {
-        const sb3 = require('./serialization/sb3');
         return StringUtil.stringify(sb3.serialize(this.runtime, optTargetId));
     }
 
@@ -495,11 +495,9 @@ class VirtualMachine extends EventEmitter {
         const deserializePromise = function () {
             const projectVersion = projectJSON.projectVersion;
             if (projectVersion === 2) {
-                const sb2 = require('./serialization/sb2');
                 return sb2.deserialize(projectJSON, runtime, false, zip);
             }
             if (projectVersion === 3) {
-                const sb3 = require('./serialization/sb3');
                 return sb3.deserialize(projectJSON, runtime, zip);
             }
             // TODO: reject with an Error (possible breaking API change!)
@@ -589,7 +587,6 @@ class VirtualMachine extends EventEmitter {
         }
 
         const validationPromise = new Promise((resolve, reject) => {
-            const validate = require('scratch-parser');
             // The second argument of true below indicates to the parser/validator
             // that the given input should be treated as a single sprite and not
             // an entire project
@@ -632,8 +629,6 @@ class VirtualMachine extends EventEmitter {
      */
     _addSprite2 (sprite, zip) {
         // Validate & parse
-
-        const sb2 = require('./serialization/sb2');
         return sb2.deserialize(sprite, this.runtime, true, zip)
             .then(({targets, extensions}) =>
                 this.installTargets(targets, extensions, false));
@@ -647,7 +642,6 @@ class VirtualMachine extends EventEmitter {
      */
     _addSprite3 (sprite, zip) {
         // Validate & parse
-        const sb3 = require('./serialization/sb3');
         return sb3
             .deserialize(sprite, this.runtime, zip, true)
             .then(({targets, extensions}) => this.installTargets(targets, extensions, false));
@@ -1247,8 +1241,6 @@ class VirtualMachine extends EventEmitter {
      * @return {!Promise} Promise that resolves when the extensions and blocks have been added.
      */
     shareBlocksToTarget (blocks, targetId, optFromTargetId) {
-        const sb3 = require('./serialization/sb3');
-
         const copiedBlocks = JSON.parse(JSON.stringify(blocks));
         newBlockIds(copiedBlocks);
         const target = this.runtime.getTargetById(targetId);
@@ -1583,4 +1575,4 @@ class VirtualMachine extends EventEmitter {
     }
 }
 
-module.exports = VirtualMachine;
+export default VirtualMachine;