diff --git a/examples/with-dynamic-import/next.config.js b/examples/with-dynamic-import/next.config.js
new file mode 100644
index 00000000..919b7305
--- /dev/null
+++ b/examples/with-dynamic-import/next.config.js
@@ -0,0 +1,8 @@
+module.exports = {
+  exportPathMap: function () {
+    return {
+      '/': { page: '/' },
+      '/about': { page: '/about' }
+    }
+  }
+}
diff --git a/examples/with-dynamic-import/package.json b/examples/with-dynamic-import/package.json
index 1c48a0e7..d88d802d 100644
--- a/examples/with-dynamic-import/package.json
+++ b/examples/with-dynamic-import/package.json
@@ -6,11 +6,11 @@
   "scripts": {
     "dev": "next",
     "build": "next build",
+    "export": "next export",
     "start": "next start"
   },
   "dependencies": {
-    "async-reactor": "^1.1.1",
-    "next": "^3.0.1-beta.5",
+    "next": "^3.0.6",
     "react": "^15.4.2",
     "react-dom": "^15.4.2"
   },
diff --git a/examples/with-dynamic-import/pages/index.js b/examples/with-dynamic-import/pages/index.js
index 5df4ae7e..6e4a9a01 100644
--- a/examples/with-dynamic-import/pages/index.js
+++ b/examples/with-dynamic-import/pages/index.js
@@ -3,7 +3,6 @@ import Router from 'next/router'
 import Header from '../components/Header'
 import Counter from '../components/Counter'
 import dynamic from 'next/dynamic'
-import { asyncReactor } from 'async-reactor'
 
 const DynamicComponent = dynamic(import('../components/hello1'))
 const DynamicComponentWithCustomLoading = dynamic(
@@ -16,11 +15,6 @@ const DynamicComponentWithNoSSR = dynamic(
   import('../components/hello3'),
   { ssr: false }
 )
-const DynamicComponentWithAsyncReactor = asyncReactor(async () => {
-  const Hello4 = await import('../components/hello4')
-  return (<Hello4 />)
-})
-
 const DynamicComponent5 = dynamic(import('../components/hello5'))
 
 const DynamicBundle = dynamic({
@@ -67,7 +61,6 @@ export default class Index extends React.Component {
         <DynamicComponent />
         <DynamicComponentWithCustomLoading />
         <DynamicComponentWithNoSSR />
-        <DynamicComponentWithAsyncReactor />
         <DynamicBundle showMore={showMore} />
         <button onClick={() => this.toggleShowMore()}>Toggle Show More</button>
         {
diff --git a/server/build/index.js b/server/build/index.js
index 90d2fe5a..92682dd6 100644
--- a/server/build/index.js
+++ b/server/build/index.js
@@ -8,13 +8,14 @@ import replaceCurrentBuild from './replace'
 import md5File from 'md5-file/promise'
 
 export default async function build (dir, conf = null) {
+  const buildId = uuid.v4()
   const buildDir = join(tmpdir(), uuid.v4())
-  const compiler = await webpack(dir, { buildDir, conf })
+  const compiler = await webpack(dir, { buildId, buildDir, conf })
 
   try {
     await runCompiler(compiler)
     await writeBuildStats(buildDir)
-    await writeBuildId(buildDir)
+    await writeBuildId(buildDir, buildId)
   } catch (err) {
     console.error(`> Failed to build on ${buildDir}`)
     throw err
@@ -59,8 +60,7 @@ async function writeBuildStats (dir) {
   await fs.writeFile(buildStatsPath, JSON.stringify(assetHashMap), 'utf8')
 }
 
-async function writeBuildId (dir) {
+async function writeBuildId (dir, buildId) {
   const buildIdPath = join(dir, '.next', 'BUILD_ID')
-  const buildId = uuid.v4()
   await fs.writeFile(buildIdPath, buildId, 'utf8')
 }
diff --git a/server/build/webpack.js b/server/build/webpack.js
index 7fd93d57..eb743758 100644
--- a/server/build/webpack.js
+++ b/server/build/webpack.js
@@ -27,7 +27,7 @@ const interpolateNames = new Map(defaultPages.map((p) => {
 
 const relativeResolve = rootModuleRelativePath(require)
 
-export default async function createCompiler (dir, { dev = false, quiet = false, buildDir, conf = null } = {}) {
+export default async function createCompiler (dir, { buildId, dev = false, quiet = false, buildDir, conf = null } = {}) {
   dir = resolve(dir)
   const config = getConfig(dir, conf)
   const defaultEntries = dev ? [
@@ -296,7 +296,7 @@ export default async function createCompiler (dir, { dev = false, quiet = false,
       path: buildDir ? join(buildDir, '.next') : join(dir, config.distDir),
       filename: '[name]',
       libraryTarget: 'commonjs2',
-      publicPath: '/_next/webpack/',
+      publicPath: `/_next/${buildId}/webpack/`,
       strictModuleExceptionHandling: true,
       devtoolModuleFilenameTemplate ({ resourcePath }) {
         const hash = createHash('sha1')
diff --git a/server/document.js b/server/document.js
index 402c105f..a536f2d7 100644
--- a/server/document.js
+++ b/server/document.js
@@ -67,12 +67,12 @@ export class Head extends Component {
 
   getPreloadDynamicChunks () {
     const { chunks, __NEXT_DATA__ } = this.context._documentProps
-    let { assetPrefix } = __NEXT_DATA__
+    let { assetPrefix, buildId } = __NEXT_DATA__
     return chunks.map((chunk) => (
       <link
         key={chunk}
         rel='preload'
-        href={`${assetPrefix}/_next/webpack/chunks/${chunk}`}
+        href={`${assetPrefix}/_next/${buildId}/webpack/chunks/${chunk}`}
         as='script'
       />
     ))
@@ -153,7 +153,7 @@ export class NextScript extends Component {
 
   getDynamicChunks () {
     const { chunks, __NEXT_DATA__ } = this.context._documentProps
-    let { assetPrefix } = __NEXT_DATA__
+    let { assetPrefix, buildId } = __NEXT_DATA__
     return (
       <div>
         {chunks.map((chunk) => (
@@ -161,7 +161,7 @@ export class NextScript extends Component {
             async
             key={chunk}
             type='text/javascript'
-            src={`${assetPrefix}/_next/webpack/chunks/${chunk}`}
+            src={`${assetPrefix}/_next/${buildId}/webpack/chunks/${chunk}`}
           />
         ))}
       </div>
diff --git a/server/export.js b/server/export.js
index 5f1818fc..fe098740 100644
--- a/server/export.js
+++ b/server/export.js
@@ -51,10 +51,10 @@ export default async function (dir, options) {
   if (existsSync(join(nextDir, 'chunks'))) {
     log('  copying dynamic import chunks')
 
-    await mkdirp(join(outDir, '_next', 'webpack'))
+    await mkdirp(join(outDir, '_next', buildId, 'webpack'))
     await cp(
       join(nextDir, 'chunks'),
-      join(outDir, '_next', 'webpack', 'chunks')
+      join(outDir, '_next', buildId, 'webpack', 'chunks')
     )
   }
 
diff --git a/server/hot-reloader.js b/server/hot-reloader.js
index cd429390..3cebfb28 100644
--- a/server/hot-reloader.js
+++ b/server/hot-reloader.js
@@ -5,6 +5,7 @@ import onDemandEntryHandler from './on-demand-entry-handler'
 import webpack from './build/webpack'
 import clean from './build/clean'
 import getConfig from './config'
+import UUID from 'uuid'
 import {
   IS_BUNDLED_PAGE
 } from './utils'
@@ -23,6 +24,11 @@ export default class HotReloader {
     this.prevChunkNames = null
     this.prevFailedChunkNames = null
     this.prevChunkHashes = null
+    // Here buildId could be any value.
+    // Our router accepts any value in the dev mode.
+    // But for the webpack-compiler and for the webpack-dev-server
+    // it should be the same value.
+    this.buildId = UUID.v4()
 
     this.config = getConfig(dir, conf)
   }
@@ -40,7 +46,7 @@ export default class HotReloader {
 
   async start () {
     const [compiler] = await Promise.all([
-      webpack(this.dir, { dev: true, quiet: this.quiet }),
+      webpack(this.dir, { buildId: this.buildId, dev: true, quiet: this.quiet }),
       clean(this.dir)
     ])
 
@@ -66,7 +72,7 @@ export default class HotReloader {
     this.stats = null
 
     const [compiler] = await Promise.all([
-      webpack(this.dir, { dev: true, quiet: this.quiet }),
+      webpack(this.dir, { buildId: this.buildId, dev: true, quiet: this.quiet }),
       clean(this.dir)
     ])
 
@@ -173,7 +179,7 @@ export default class HotReloader {
     ]
 
     let webpackDevMiddlewareConfig = {
-      publicPath: '/_next/webpack/',
+      publicPath: `/_next/${this.buildId}/webpack/`,
       noInfo: true,
       quiet: true,
       clientLogLevel: 'warning',
diff --git a/server/index.js b/server/index.js
index 1900ccfd..6b453135 100644
--- a/server/index.js
+++ b/server/index.js
@@ -123,14 +123,21 @@ export default class Server {
       },
 
       // This is to support, webpack dynamic imports in production.
-      '/_next/webpack/chunks/:name': async (req, res, params) => {
-        res.setHeader('Cache-Control', 'max-age=365000000, immutable')
+      '/_next/:buildId/webpack/chunks/:name': async (req, res, params) => {
+        if (!this.handleBuildId(params.buildId, res)) {
+          return this.send404(res)
+        }
+
         const p = join(this.dir, this.dist, 'chunks', params.name)
         await this.serveStatic(req, res, p)
       },
 
       // This is to support, webpack dynamic import support with HMR
-      '/_next/webpack/:id': async (req, res, params) => {
+      '/_next/:buildId/webpack/:id': async (req, res, params) => {
+        if (!this.handleBuildId(params.buildId, res)) {
+          return this.send404(res)
+        }
+
         const p = join(this.dir, this.dist, 'chunks', params.id)
         await this.serveStatic(req, res, p)
       },