diff --git a/test/common/inspector-helper.js b/test/common/inspector-helper.js
index 48c9e5f1d17141..359f586344cb9e 100644
--- a/test/common/inspector-helper.js
+++ b/test/common/inspector-helper.js
@@ -372,7 +372,7 @@ class NodeInstance extends EventEmitter {
 
   static async startViaSignal(scriptContents) {
     const instance = new NodeInstance(
-      ['--expose-internals'],
+      ['--expose-internals', '--inspect-port=0'],
       `${scriptContents}\nprocess._rawDebug('started');`, undefined);
     const msg = 'Timed out waiting for process to start';
     while (await fires(instance.nextStderrString(), msg, TIMEOUT) !== 'started');