diff --git a/lib/routes.js b/lib/routes.js
index 6d78eda..54369b9 100644
--- a/lib/routes.js
+++ b/lib/routes.js
@@ -9,9 +9,10 @@
   included in all copies or substantial portions of this Source Code Form.
 */
 const router = require('koa-route');
+const stringify = require('safe-stable-stringify');
 const stripAnsi = require('strip-ansi');
 
-const prep = (data) => JSON.stringify(data);
+const prep = (data) => stringify(data);
 
 const statsOptions = {
   all: false,
diff --git a/package-lock.json b/package-lock.json
index 7fd8009..2b11e08 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -10296,6 +10296,12 @@
       "integrity": "sha1-Q2CxfGETatOAeDl/8RQW4Ybc+7g=",
       "dev": true
     },
+    "random-js": {
+      "version": "2.1.0",
+      "resolved": "https://registry.npmjs.org/random-js/-/random-js-2.1.0.tgz",
+      "integrity": "sha512-CRUyWmnzmZBA7RZSVGq0xMqmgCyPPxbiKNLFA5ud7KenojVX2s7Gv+V7eB52beKTPGxWRnVZ7D/tCIgYJJ8vNQ==",
+      "dev": true
+    },
     "randombytes": {
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/randombytes/-/randombytes-2.1.0.tgz",
@@ -10813,6 +10819,11 @@
         "ret": "~0.1.10"
       }
     },
+    "safe-stable-stringify": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/safe-stable-stringify/-/safe-stable-stringify-1.1.1.tgz",
+      "integrity": "sha512-ERq4hUjKDbJfE4+XtZLFPCDi8Vb1JqaxAPTxWFLBx8XcAlf9Bda/ZJdVezs/NAfsMQScyIlUMx+Yeu7P7rx5jw=="
+    },
     "safer-buffer": {
       "version": "2.1.2",
       "resolved": "https://registry.npmjs.org/safer-buffer/-/safer-buffer-2.1.2.tgz",
diff --git a/package.json b/package.json
index ba0a0fd..08ca790 100644
--- a/package.json
+++ b/package.json
@@ -56,6 +56,7 @@
     "open": "^7.0.3",
     "p-defer": "^3.0.0",
     "rimraf": "^3.0.2",
+    "safe-stable-stringify": "^1.1.1",
     "strip-ansi": "^6.0.0",
     "superstruct": "^0.11.1",
     "webpack-plugin-ramdisk": "^0.1.2",
@@ -77,6 +78,7 @@
     "nyc": "^15.0.1",
     "pre-commit": "^1.2.2",
     "puppeteer": "^3.0.2",
+    "random-js": "^2.1.0",
     "react-refresh": "^0.8.3",
     "webpack": "^4.44.2",
     "webpack-nano": "^1.0.0"
diff --git a/test/fixtures/multi/webpack.config.js b/test/fixtures/multi/webpack.config.js
index 9d13442..43b950b 100644
--- a/test/fixtures/multi/webpack.config.js
+++ b/test/fixtures/multi/webpack.config.js
@@ -1,12 +1,12 @@
 const { resolve } = require('path');
 
-const getPort = require('get-port');
+const { getPort } = require('../../helpers/port');
 
 const { WebpackPluginServe: Serve } = require('../../../lib/');
 
 const serve = new Serve({
   host: 'localhost',
-  port: getPort({ port: 55555 })
+  port: getPort()
 });
 
 module.exports = [
diff --git a/test/fixtures/ramdisk-empty-pkg/webpack.config.js b/test/fixtures/ramdisk-empty-pkg/webpack.config.js
index 3a4d0bb..59c4271 100644
--- a/test/fixtures/ramdisk-empty-pkg/webpack.config.js
+++ b/test/fixtures/ramdisk-empty-pkg/webpack.config.js
@@ -1,6 +1,6 @@
 const { resolve } = require('path');
 
-const getPort = require('get-port');
+const { getPort } = require('../../helpers/port');
 
 const { WebpackPluginServe: Serve } = require('../../../lib/');
 
@@ -16,7 +16,7 @@ module.exports = {
   plugins: [
     new Serve({
       host: 'localhost',
-      port: getPort({ port: 55555 }),
+      port: getPort(),
       ramdisk: true
     })
   ],
diff --git a/test/fixtures/ramdisk/config-context-error.js b/test/fixtures/ramdisk/config-context-error.js
index fa0f821..3348781 100644
--- a/test/fixtures/ramdisk/config-context-error.js
+++ b/test/fixtures/ramdisk/config-context-error.js
@@ -1,6 +1,6 @@
 const { resolve } = require('path');
 
-const getPort = require('get-port');
+const { getPort } = require('../../helpers/port');
 
 const { WebpackPluginServe: Serve } = require('../../../lib/');
 
@@ -16,7 +16,7 @@ module.exports = {
   plugins: [
     new Serve({
       host: 'localhost',
-      port: getPort({ port: 55555 }),
+      port: getPort(),
       ramdisk: true
     })
   ],
diff --git a/test/fixtures/ramdisk/config-cwd-error.js b/test/fixtures/ramdisk/config-cwd-error.js
index b21c810..123697d 100644
--- a/test/fixtures/ramdisk/config-cwd-error.js
+++ b/test/fixtures/ramdisk/config-cwd-error.js
@@ -1,6 +1,6 @@
 const { resolve } = require('path');
 
-const getPort = require('get-port');
+const { getPort } = require('../../helpers/port');
 
 const { WebpackPluginServe: Serve } = require('../../../lib/');
 
@@ -16,7 +16,7 @@ module.exports = {
   plugins: [
     new Serve({
       host: 'localhost',
-      port: getPort({ port: 55555 }),
+      port: getPort(),
       ramdisk: true
     })
   ],
diff --git a/test/fixtures/ramdisk/custom-options.js b/test/fixtures/ramdisk/custom-options.js
index 0961acf..af32db6 100644
--- a/test/fixtures/ramdisk/custom-options.js
+++ b/test/fixtures/ramdisk/custom-options.js
@@ -1,6 +1,6 @@
 const { resolve } = require('path');
 
-const getPort = require('get-port');
+const { getPort } = require('../../helpers/port');
 
 const { WebpackPluginServe: Serve } = require('../../../lib/');
 
@@ -16,7 +16,7 @@ module.exports = {
   plugins: [
     new Serve({
       host: 'localhost',
-      port: getPort({ port: 55555 }),
+      port: getPort(),
       ramdisk: {
         bytes: 1024 * 1024
       }
diff --git a/test/fixtures/ramdisk/webpack.config.js b/test/fixtures/ramdisk/webpack.config.js
index 3a4d0bb..59c4271 100644
--- a/test/fixtures/ramdisk/webpack.config.js
+++ b/test/fixtures/ramdisk/webpack.config.js
@@ -1,6 +1,6 @@
 const { resolve } = require('path');
 
-const getPort = require('get-port');
+const { getPort } = require('../../helpers/port');
 
 const { WebpackPluginServe: Serve } = require('../../../lib/');
 
@@ -16,7 +16,7 @@ module.exports = {
   plugins: [
     new Serve({
       host: 'localhost',
-      port: getPort({ port: 55555 }),
+      port: getPort(),
       ramdisk: true
     })
   ],
diff --git a/test/fixtures/simple/webpack.config.js b/test/fixtures/simple/webpack.config.js
index e3a089d..0144965 100644
--- a/test/fixtures/simple/webpack.config.js
+++ b/test/fixtures/simple/webpack.config.js
@@ -1,6 +1,6 @@
 const { resolve } = require('path');
 
-const getPort = require('get-port');
+const { getPort } = require('../../helpers/port');
 
 const { WebpackPluginServe: Serve } = require('../../../lib/');
 
@@ -19,7 +19,7 @@ module.exports = {
         'X-Superhero': 'batman'
       },
       host: 'localhost',
-      port: getPort({ port: 55555 })
+      port: getPort()
     })
   ],
   resolve: {
diff --git a/test/helpers/port.js b/test/helpers/port.js
new file mode 100644
index 0000000..b92585f
--- /dev/null
+++ b/test/helpers/port.js
@@ -0,0 +1,8 @@
+const getPort = require('get-port');
+const { Random } = require('random-js');
+
+const random = new Random();
+
+module.exports = {
+  getPort: () => getPort({ port: random.integer(55000, 55555) })
+};
diff --git a/test/ramdisk.test.js b/test/ramdisk.test.js
index ec8457d..a20764c 100644
--- a/test/ramdisk.test.js
+++ b/test/ramdisk.test.js
@@ -22,7 +22,7 @@ const waitFor = (text, stream) => {
   };
 };
 
-test('ramdisk', async (t) => {
+test.serial('ramdisk', async (t) => {
   const proc = execa('wp', [], { cwd: fixturePath });
   const { stderr, stdout } = proc;
   const pathTest = 'Build being written to ';
@@ -41,7 +41,7 @@ test('ramdisk', async (t) => {
   proc.kill('SIGTERM');
 });
 
-test('ramdisk with options', async (t) => {
+test.serial('ramdisk with options', async (t) => {
   const proc = execa('wp', ['--config', 'ramdisk/custom-options.js'], {
     cwd: resolve(fixturePath, '..')
   });
@@ -62,7 +62,7 @@ test('ramdisk with options', async (t) => {
   proc.kill('SIGTERM');
 });
 
-test('context error', async (t) => {
+test.serial('context error', async (t) => {
   try {
     await execa('wp', ['--config', 'ramdisk/config-context-error.js'], {
       cwd: resolve(fixturePath, '..')
@@ -75,7 +75,7 @@ test('context error', async (t) => {
   t.fail();
 });
 
-test('cwd error', async (t) => {
+test.serial('cwd error', async (t) => {
   try {
     await execa('wp', ['--config', '../config-cwd-error.js'], {
       cwd: join(fixturePath, 'cwd-error')
@@ -88,7 +88,7 @@ test('cwd error', async (t) => {
   t.fail();
 });
 
-test('ramdisk with empty package.json', async (t) => {
+test.serial('ramdisk with empty package.json', async (t) => {
   const fixturePath = join(__dirname, 'fixtures/ramdisk-empty-pkg');
   const proc = execa('wp', [], { cwd: fixturePath });
   const { stderr, stdout } = proc;
diff --git a/test/wait-for-build.test.js b/test/wait-for-build.test.js
index d59b3b8..a0e4faa 100644
--- a/test/wait-for-build.test.js
+++ b/test/wait-for-build.test.js
@@ -1,10 +1,10 @@
-const getPort = require('get-port');
 const del = require('del');
 const webpack = require('webpack');
 const test = require('ava');
 const fetch = require('node-fetch');
 const defer = require('p-defer');
 
+const { getPort } = require('./helpers/port');
 const { make } = require('./fixtures/wait-for-build/make-config');
 
 let watcher;
diff --git a/test/ws.test.js b/test/ws.test.js
index 0ae7fa6..1e00dd5 100644
--- a/test/ws.test.js
+++ b/test/ws.test.js
@@ -1,5 +1,4 @@
 const test = require('ava');
-const getPort = require('get-port');
 const Koa = require('koa');
 const router = require('koa-route');
 const defer = require('p-defer');
@@ -7,6 +6,8 @@ const WebSocket = require('ws');
 
 const { middleware } = require('../lib/ws');
 
+const { getPort } = require('./helpers/port');
+
 test('websocket middleware', async (t) => {
   const app = new Koa();
   const port = await getPort();