diff --git a/lib/internal/cluster/round_robin_handle.js b/lib/internal/cluster/round_robin_handle.js
index e351f433ab8c7e..9f09d9fbf76635 100644
--- a/lib/internal/cluster/round_robin_handle.js
+++ b/lib/internal/cluster/round_robin_handle.js
@@ -2,7 +2,6 @@
 const assert = require('assert');
 const net = require('net');
 const { sendHelper } = require('internal/cluster/utils');
-const getOwnPropertyNames = Object.getOwnPropertyNames;
 const { internalBinding } = require('internal/bootstrap/loaders');
 const uv = internalBinding('uv');
 
@@ -10,7 +9,7 @@ module.exports = RoundRobinHandle;
 
 function RoundRobinHandle(key, address, port, addressType, fd) {
   this.key = key;
-  this.all = {};
+  this.all = new Map();
   this.free = [];
   this.handles = [];
   this.handle = null;
@@ -32,8 +31,8 @@ function RoundRobinHandle(key, address, port, addressType, fd) {
 }
 
 RoundRobinHandle.prototype.add = function(worker, send) {
-  assert(worker.id in this.all === false);
-  this.all[worker.id] = worker;
+  assert(this.all.has(worker.id) === false);
+  this.all.set(worker.id, worker);
 
   const done = () => {
     if (this.handle.getsockname) {
@@ -62,16 +61,17 @@ RoundRobinHandle.prototype.add = function(worker, send) {
 };
 
 RoundRobinHandle.prototype.remove = function(worker) {
-  if (worker.id in this.all === false)
+  const existed = this.all.delete(worker.id);
+
+  if (!existed)
     return false;
 
-  delete this.all[worker.id];
   const index = this.free.indexOf(worker);
 
   if (index !== -1)
     this.free.splice(index, 1);
 
-  if (getOwnPropertyNames(this.all).length !== 0)
+  if (this.all.size !== 0)
     return false;
 
   for (var handle; handle = this.handles.shift(); handle.close())
@@ -91,7 +91,7 @@ RoundRobinHandle.prototype.distribute = function(err, handle) {
 };
 
 RoundRobinHandle.prototype.handoff = function(worker) {
-  if (worker.id in this.all === false) {
+  if (this.all.has(worker.id) === false) {
     return;  // Worker is closing (or has closed) the server.
   }