diff --git a/test/fixtures/clustered-server/app.js b/test/fixtures/clustered-server/app.js
index cae204c25bd043..16ac62fca847dc 100644
--- a/test/fixtures/clustered-server/app.js
+++ b/test/fixtures/clustered-server/app.js
@@ -1,12 +1,13 @@
-var http = require('http');
-var cluster = require('cluster');
-var common = require('../../common');
+'use strict';
+
+const http = require('http');
+const cluster = require('cluster');
 
 function handleRequest(request, response) {
   response.end('hello world\n');
 }
 
-var NUMBER_OF_WORKERS = 2;
+const NUMBER_OF_WORKERS = 2;
 var workersOnline = 0;
 
 if (cluster.isMaster) {
@@ -18,7 +19,7 @@ if (cluster.isMaster) {
 
   process.on('message', function(msg) {
     if (msg.type === 'getpids') {
-      var pids = [];
+      const pids = [];
       pids.push(process.pid);
       for (var key in cluster.workers)
         pids.push(cluster.workers[key].process.pid);
@@ -30,6 +31,6 @@ if (cluster.isMaster) {
     cluster.fork();
   }
 } else {
-  var server = http.createServer(handleRequest);
-  server.listen(common.PORT);
+  const server = http.createServer(handleRequest);
+  server.listen(0);
 }
diff --git a/test/parallel/test-debug-signal-cluster.js b/test/parallel/test-debug-signal-cluster.js
index 31b42058daab48..8cda7d3567726c 100644
--- a/test/parallel/test-debug-signal-cluster.js
+++ b/test/parallel/test-debug-signal-cluster.js
@@ -1,21 +1,23 @@
 'use strict';
-var common = require('../common');
-var assert = require('assert');
-var spawn = require('child_process').spawn;
 
-var port = common.PORT + 1;  // The fixture uses common.PORT.
-var args = ['--debug-port=' + port,
-            common.fixturesDir + '/clustered-server/app.js'];
-var options = { stdio: ['inherit', 'inherit', 'pipe', 'ipc'] };
-var child = spawn(process.execPath, args, options);
+const common = require('../common');
+const assert = require('assert');
+const spawn = require('child_process').spawn;
+const path = require('path');
 
-var outputLines = [];
+const port = common.PORT;
+const serverPath = path.join(common.fixturesDir, 'clustered-server', 'app.js');
+const args = [`--debug-port=${port}`, serverPath];
+const options = { stdio: ['inherit', 'inherit', 'pipe', 'ipc'] };
+const child = spawn(process.execPath, args, options);
+
+const outputLines = [];
 var waitingForDebuggers = false;
 
-var pids = null;
+var pids;
 
 child.stderr.on('data', function(data) {
-  var lines = data.toString().replace(/\r/g, '').trim().split('\n');
+  const lines = data.toString().replace(/\r/g, '').trim().split('\n');
 
   lines.forEach(function(line) {
     console.log('> ' + line);
@@ -40,7 +42,7 @@ child.stderr.on('data', function(data) {
     }
 
   });
-  if (outputLines.length >= expectedLines.length)
+  if (outputLines.length === expectedLines.length)
     onNoMoreLines();
 });
 
@@ -50,7 +52,7 @@ function onNoMoreLines() {
 }
 
 setTimeout(function testTimedOut() {
-  assert(false, 'test timed out.');
+  common.fail('test timed out');
 }, common.platformTimeout(4000)).unref();
 
 process.on('exit', function onExit() {
@@ -61,7 +63,7 @@ process.on('exit', function onExit() {
   });
 });
 
-var expectedLines = [
+const expectedLines = [
   'Starting debugger agent.',
   'Debugger listening on 127.0.0.1:' + (port + 0),
   'Starting debugger agent.',
@@ -77,7 +79,5 @@ function assertOutputLines() {
   outputLines.sort();
   expectedLines.sort();
 
-  assert.equal(outputLines.length, expectedLines.length);
-  for (var i = 0; i < expectedLines.length; i++)
-    assert(expectedLines[i].includes(outputLines[i]));
+  assert.deepStrictEqual(outputLines, expectedLines);
 }