diff --git a/packages/next-server/server/next-server.ts b/packages/next-server/server/next-server.ts
index 54b15b49..22a544a2 100644
--- a/packages/next-server/server/next-server.ts
+++ b/packages/next-server/server/next-server.ts
@@ -224,7 +224,7 @@ export default class Server {
     }
 
     if (this.nextConfig.poweredByHeader) {
-      res.setHeader('X-Powered-By', 'Next.js ' + process.env.NEXT_VERSION)
+      res.setHeader('X-Powered-By', 'Next.js ' + process.env.__NEXT_VERSION)
     }
     return this.sendHTML(req, res, html)
   }
diff --git a/packages/next-server/taskfile-typescript.js b/packages/next-server/taskfile-typescript.js
index f200e935..cb1d460a 100644
--- a/packages/next-server/taskfile-typescript.js
+++ b/packages/next-server/taskfile-typescript.js
@@ -35,7 +35,7 @@ try {
       }
 
       // update file's data
-      file.data = Buffer.from(result.outputText.replace(/process\.env\.NEXT_VERSION/, `"${require('./package.json').version}"`), 'utf8')
+      file.data = Buffer.from(result.outputText.replace(/process\.env\.__NEXT_VERSION/, `"${require('./package.json').version}"`), 'utf8')
     })
   }
 } catch (err) {
diff --git a/packages/next/bin/next.ts b/packages/next/bin/next.ts
index c4d1fc1e..515d04ba 100755
--- a/packages/next/bin/next.ts
+++ b/packages/next/bin/next.ts
@@ -37,7 +37,7 @@ const args = arg({
 // Version is inlined into the file using taskr build pipeline
 if (args['--version']) {
   // tslint:disable-next-line
-  console.log(`Next.js v${process.env.NEXT_VERSION}`)
+  console.log(`Next.js v${process.env.__NEXT_VERSION}`)
   process.exit(0)
 }
 
diff --git a/packages/next/build/webpack-config.js b/packages/next/build/webpack-config.js
index 2c9efae0..c2475bf6 100644
--- a/packages/next/build/webpack-config.js
+++ b/packages/next/build/webpack-config.js
@@ -295,7 +295,7 @@ export default async function getBaseWebpackConfig (dir, {dev = false, isServer
         {},
         config.env ? Object.keys(config.env)
           .reduce((acc, key) => {
-            if (/^(?:NODE_\w+)|(?:NEXT_\w+)|(?:__\w+)|(?:CONFIG_BUILD_ID)|(?:PORT)$/.test(key.toUpperCase())) throw new Error(`Next.js config env cannot have key of ${key}`)
+            if (/^(?:NODE_.+)|(?:__.+)$/.test(key.toUpperCase())) throw new Error(`Next.js config env cannot have key of ${key}`)
             return {
               ...acc,
               ...{ [`process.env.${key}`]: JSON.stringify(config.env[key]) }
diff --git a/packages/next/client/on-demand-entries-client.js b/packages/next/client/on-demand-entries-client.js
index 210b102b..2f67e3df 100644
--- a/packages/next/client/on-demand-entries-client.js
+++ b/packages/next/client/on-demand-entries-client.js
@@ -20,7 +20,7 @@ export default async ({ assetPrefix }) => {
     }
 
     return new Promise(resolve => {
-      ws = new WebSocket(`${wsProtocol}://${hostname}:${process.env.NEXT_WS_PORT}${process.env.NEXT_WS_PROXY_PATH}`)
+      ws = new WebSocket(`${wsProtocol}://${hostname}:${process.env.__NEXT_WS_PORT}${process.env.__NEXT_WS_PROXY_PATH}`)
       ws.onopen = () => resolve()
       ws.onclose = () => {
         setTimeout(async () => {
diff --git a/packages/next/server/hot-reloader.js b/packages/next/server/hot-reloader.js
index deb31164..8e32b5ae 100644
--- a/packages/next/server/hot-reloader.js
+++ b/packages/next/server/hot-reloader.js
@@ -167,8 +167,8 @@ export default class HotReloader {
   addWsConfig (configs) {
     const { websocketProxyPath, websocketProxyPort } = this.config.onDemandEntries
     const opts = {
-      'process.env.NEXT_WS_PORT': websocketProxyPort || this.wsPort,
-      'process.env.NEXT_WS_PROXY_PATH': JSON.stringify(websocketProxyPath)
+      'process.env.__NEXT_WS_PORT': websocketProxyPort || this.wsPort,
+      'process.env.__NEXT_WS_PROXY_PATH': JSON.stringify(websocketProxyPath)
     }
     configs[0].plugins.push(new webpack.DefinePlugin(opts))
   }
diff --git a/packages/next/taskfile-typescript.js b/packages/next/taskfile-typescript.js
index 39482e2e..2f4f5b89 100644
--- a/packages/next/taskfile-typescript.js
+++ b/packages/next/taskfile-typescript.js
@@ -40,7 +40,7 @@ try {
       if (file.base === 'next-dev.js') result.outputText = result.outputText.replace('// REPLACE_NOOP_IMPORT', `import('./noop');`)
 
       // update file's data
-      file.data = Buffer.from(result.outputText.replace(/process\.env\.NEXT_VERSION/, `"${require('./package.json').version}"`), 'utf8')
+      file.data = Buffer.from(result.outputText.replace(/process\.env\.__NEXT_VERSION/, `"${require('./package.json').version}"`), 'utf8')
     })
   }
 } catch (err) {