diff --git a/.eslintrc.yml b/.eslintrc.yml
index 2d4721b8ed..77037f48b3 100644
--- a/.eslintrc.yml
+++ b/.eslintrc.yml
@@ -24,6 +24,7 @@ overrides:
       - bin/*
       - lib/cli/**/*.js
       - test/node-unit/**/*.js
+      - lib/growl.js
     parserOptions:
       ecmaVersion: 6
     env:
diff --git a/lib/growl.js b/lib/growl.js
index ee3d23232a..eae2281823 100644
--- a/lib/growl.js
+++ b/lib/growl.js
@@ -5,9 +5,9 @@
  * @module Growl
  */
 
-var fs = require('fs');
-var os = require('os');
-var path = require('path');
+const os = require('os');
+const path = require('path');
+const {sync: which} = require('which');
 
 /**
  * @summary
@@ -23,8 +23,14 @@ var path = require('path');
  * @see {@link Mocha#isGrowlCapable}
  * @return {boolean} whether Growl notification support can be expected
  */
-exports.isCapable = function() {
-  return !process.browser && which(getSupportBinaries()) !== '';
+exports.isCapable = () => {
+  if (!process.browser) {
+    return getSupportBinaries().reduce(
+      (acc, binary) => acc || Boolean(which(binary, {nothrow: true})),
+      false
+    );
+  }
+  return false;
 };
 
 /**
@@ -34,11 +40,10 @@ exports.isCapable = function() {
  * @see {@link Mocha#_growl}
  * @param {Runner} runner - Runner instance.
  */
-exports.notify = function(runner) {
-  var sendNotification = function() {
+exports.notify = runner => {
+  runner.once('end', () => {
     display(runner);
-  };
-  runner.once('end', sendNotification);
+  });
 };
 
 /**
@@ -47,35 +52,35 @@ exports.notify = function(runner) {
  * @private
  * @param {Runner} runner - Runner instance.
  */
-function display(runner) {
-  var growl = require('growl');
-  var stats = runner.stats;
-  var symbol = {
+const display = runner => {
+  const growl = require('growl');
+  const stats = runner.stats;
+  const symbol = {
     cross: '\u274C',
     tick: '\u2705'
   };
-  var _message;
-  var message;
-  var title;
+  let _message;
+  let message;
+  let title;
 
   if (stats.failures) {
-    _message = stats.failures + ' of ' + runner.total + ' tests failed';
-    message = symbol.cross + ' ' + _message;
+    _message = `${stats.failures} of ${runner.total} tests failed`;
+    message = `${symbol.cross} ${_message}`;
     title = 'Failed';
   } else {
-    _message = stats.passes + ' tests passed in ' + stats.duration + 'ms';
-    message = symbol.tick + ' ' + _message;
+    _message = `${stats.passes} tests passed in ${stats.duration}ms`;
+    message = `${symbol.tick} ${_message}`;
     title = 'Passed';
   }
 
   // Send notification
-  var options = {
+  const options = {
     image: logo(),
     name: 'mocha',
-    title: title
+    title
   };
   growl(message, options, onCompletion);
-}
+};
 
 /**
  * @summary
@@ -88,15 +93,11 @@ function display(runner) {
  * @private
  * @callback Growl~growlCB
  * @param {*} err - Error object, or <code>null</code> if successful.
- * @param {string} stdout - <code>stdout</code> from notification delivery
- *     process.
- * @param {string} stderr - <code>stderr</code> from notification delivery
- *     process. It will include timestamp and executed command with arguments.
  */
-function onCompletion(err, stdout, stderr) {
+function onCompletion(err) {
   if (err) {
     // As notifications are tangential to our purpose, just log the error.
-    var message =
+    const message =
       err.code === 'ENOENT' ? 'prerequisite software not found' : err.message;
     console.error('notification error:', message);
   }
@@ -108,36 +109,9 @@ function onCompletion(err, stdout, stderr) {
  * @private
  * @return {string} Pathname of Mocha logo
  */
-function logo() {
+const logo = () => {
   return path.join(__dirname, '..', 'assets', 'mocha-logo-96.png');
-}
-
-/**
- * @summary
- * Locates a binary in the user's `PATH` environment variable.
- *
- * @description
- * Takes a list of command names and searches the path for each executable
- * file that would be run had these commands actually been invoked.
- *
- * @private
- * @param {string[]} binaries - Names of binary files to search for.
- * @return {string} absolute path of first binary found, or empty string if none
- */
-function which(binaries) {
-  var paths = process.env.PATH.split(path.delimiter);
-
-  for (var n = 0, blen = binaries.length; n < blen; n++) {
-    var binary = binaries[n];
-    for (var i = 0, plen = paths.length; i < plen; i++) {
-      var loc = path.join(paths[i], binary);
-      if (fs.existsSync(loc)) {
-        return loc;
-      }
-    }
-  }
-  return '';
-}
+};
 
 /**
  * @summary
@@ -151,11 +125,11 @@ function which(binaries) {
  * @see {@link https://github.com/tj/node-growl/blob/master/lib/growl.js#L28-L126|setupCmd}
  * @return {string[]} names of Growl support binaries
  */
-function getSupportBinaries() {
-  var binaries = {
+const getSupportBinaries = () => {
+  const binaries = {
     Darwin: ['terminal-notifier', 'growlnotify'],
     Linux: ['notify-send', 'growl'],
     Windows_NT: ['growlnotify.exe']
   };
   return binaries[os.type()] || [];
-}
+};
diff --git a/package-lock.json b/package-lock.json
index 3de8118bc2..ff5e41de3c 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -13263,15 +13263,6 @@
         "semver": "^5.1.0"
       }
     },
-    "package-json-versionify": {
-      "version": "1.0.4",
-      "resolved": "https://registry.npmjs.org/package-json-versionify/-/package-json-versionify-1.0.4.tgz",
-      "integrity": "sha1-WGBYepRIc6a35tJujlH/siMVvxc=",
-      "dev": true,
-      "requires": {
-        "browserify-package-json": "^1.0.0"
-      }
-    },
     "pako": {
       "version": "1.0.6",
       "resolved": "https://registry.npmjs.org/pako/-/pako-1.0.6.tgz",
@@ -17850,9 +17841,9 @@
       }
     },
     "which": {
-      "version": "1.3.0",
-      "resolved": "https://registry.npmjs.org/which/-/which-1.3.0.tgz",
-      "integrity": "sha512-xcJpopdamTuY5duC/KnTTNBraPK54YwpenP4lzxU8H91GudWpFv38u0CKjclE1Wi2EH2EDz5LRcHcKbCIzqGyg==",
+      "version": "1.3.1",
+      "resolved": "https://registry.npmjs.org/which/-/which-1.3.1.tgz",
+      "integrity": "sha512-HxJdYWq1MTIQbJ3nw0cqssHoTNU267KlrDuGZ1WYlxDStUtKUhOaJmh112/TZmHxxUfuJqPXSOm7tDyas0OSIQ==",
       "requires": {
         "isexe": "^2.0.0"
       }
diff --git a/package.json b/package.json
index 96a2e48636..d7ca05579e 100644
--- a/package.json
+++ b/package.json
@@ -488,6 +488,7 @@
     "object.assign": "4.1.0",
     "strip-json-comments": "2.0.1",
     "supports-color": "^6.0.0",
+    "which": "1.3.1",
     "wide-align": "1.1.3",
     "yargs": "12.0.5",
     "yargs-parser": "11.1.1",