diff --git a/bin/webpack-dev-server.js b/bin/webpack-dev-server.js
index 4ab436d6a0..b2555abd9b 100755
--- a/bin/webpack-dev-server.js
+++ b/bin/webpack-dev-server.js
@@ -92,6 +92,8 @@ yargs.options(options);
 
 const argv = yargs.argv;
 
+process.env.WEBPACK_DEV_SERVER = true;
+
 // webpack-cli@3.3 path : 'webpack-cli/bin/utils/convert-argv'
 let convertArgvPath;
 try {
diff --git a/lib/Server.js b/lib/Server.js
index 7b5d76557e..295d7e857c 100644
--- a/lib/Server.js
+++ b/lib/Server.js
@@ -90,6 +90,8 @@ class Server {
       throw new Error("'filename' option must be set in lazy mode.");
     }
 
+    process.env.WEBPACK_DEV_SERVER = true;
+
     // if the user enables http2, we can safely enable https
     if (options.http2 && !options.https) {
       options.https = true;
diff --git a/test/Server.test.js b/test/Server.test.js
index 1c4a17bb78..002836f8e3 100644
--- a/test/Server.test.js
+++ b/test/Server.test.js
@@ -8,6 +8,13 @@ const config = require('./fixtures/simple-config/webpack.config');
 const helper = require('./helper');
 
 describe('Server', () => {
+  it('process.env.WEBPACK_DEV_SERVER', () => {
+    const compiler = webpack(config);
+    // eslint-disable-next-line no-new
+    new Server(compiler);
+    expect(process.env.WEBPACK_DEV_SERVER).toBeTruthy();
+  });
+
   describe('addEntries', () => {
     it('add hot option', () => {
       return new Promise((res) => {
diff --git a/test/cli.test.js b/test/cli.test.js
index 69b2128169..258695f6f5 100644
--- a/test/cli.test.js
+++ b/test/cli.test.js
@@ -17,6 +17,15 @@ const keyPath = path.join(httpsCertificateDirectory, 'server.key');
 const certPath = path.join(httpsCertificateDirectory, 'server.crt');
 
 describe('CLI', () => {
+  it('process.env.WEBPACK_DEV_SERVER', (done) => {
+    runDevServer()
+      .then(() => {
+        expect(process.env.WEBPACK_DEV_SERVER).toBeTruthy();
+        done();
+      })
+      .catch(done);
+  });
+
   it('--progress', (done) => {
     runDevServer('--progress')
       .then((output) => {