diff --git a/.eslintrc.json b/.eslintrc.json
index f758a8d45..9f9c9fed1 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -94,6 +94,7 @@
         "sourceType": "script"
       },
       "env": {
+        "es2020": true,
         "node": true
       },
       "rules": {
@@ -109,11 +110,11 @@
     {
       "files": ["test/cli/**"],
       "env": {
-        "es2017": true,
+        "es2020": true,
         "node": true
       },
       "parserOptions": {
-        "ecmaVersion": 2018
+        "ecmaVersion": 2020
       },
       "rules": {
         "compat/compat": "off"
diff --git a/build/tasks/test-on-node.js b/build/tasks/test-on-node.js
index a1610d0c1..e98132a71 100644
--- a/build/tasks/test-on-node.js
+++ b/build/tasks/test-on-node.js
@@ -16,25 +16,24 @@ module.exports = function (grunt) {
       grunt.log.ok(`Ran ${totals.files} files`);
     }
 
-    // Refresh the QUnit global to be used in other tests
-    global.QUnit = requireFresh('../../qunit/qunit.js');
-
     done(!totals.failed);
   });
 
-  function requireFresh (path) {
-    let resolvedPath = require.resolve(path);
+  function requireFreshQUnit () {
+    // Resolve current QUnit path and remove it from the require cache
+    // to avoid stacking the QUnit logs.
+    const path = '../../qunit/qunit.js';
+    const resolvedPath = require.resolve(path);
     delete require.cache[resolvedPath];
+
+    // Clear any QUnit global from a previous test
+    delete globalThis.QUnit;
+
     return require(path);
   }
 
   async function runQUnit (file) {
-    // Resolve current QUnit path and remove it from the require cache
-    // to avoid stacking the QUnit logs.
-    let QUnit = requireFresh('../../qunit/qunit.js');
-
-    // Expose QUnit to the global scope to be seen on the other tests.
-    global.QUnit = QUnit;
+    const QUnit = requireFreshQUnit();
 
     QUnit.config.autostart = false;
     await import('../../' + file);
diff --git a/src/cli/run.js b/src/cli/run.js
index 6b8c6a04c..9e2a2e9f9 100644
--- a/src/cli/run.js
+++ b/src/cli/run.js
@@ -43,7 +43,8 @@ async function run (args, options) {
 
   const files = utils.getFilesFromArgs(args);
 
-  QUnit = requireQUnit();
+  // Replace any previous instance, e.g. in watch mode
+  QUnit = globalThis.QUnit = requireQUnit();
 
   if (options.filter) {
     QUnit.config.filter = options.filter;
@@ -65,10 +66,6 @@ async function run (args, options) {
     console.log(`Running tests with seed: ${QUnit.config.seed}`);
   }
 
-  // TODO: Enable mode where QUnit is not auto-injected, but other setup is
-  // still done automatically.
-  global.QUnit = QUnit;
-
   options.requires.forEach(requireFromCWD);
 
   findReporter(options.reporter, QUnit.reporters).init(QUnit);
@@ -177,7 +174,7 @@ function abort (callback) {
     process.off('exit', onExit);
     running = false;
 
-    delete global.QUnit;
+    delete globalThis.QUnit;
     QUnit = null;
     if (callback) {
       callback();
@@ -192,8 +189,7 @@ run.watch = function watch (args, options) {
   const watch = require('node-watch');
   const baseDir = process.cwd();
 
-  QUnit = requireQUnit();
-  global.QUnit = QUnit;
+  requireQUnit();
   options.requires.forEach(requireFromCWD);
 
   // Include TypeScript when in use (automatically via require.extensions),
diff --git a/src/core/export.js b/src/core/export.js
index 1802f45cc..4ec44ce79 100644
--- a/src/core/export.js
+++ b/src/core/export.js
@@ -1,18 +1,29 @@
 /* global module, exports */
 import { window, document, globalThis } from './globals.js';
 
+/**
+ * Available exports:
+ *
+ * globalThis:
+ * - browser (globalThis === window)
+ * - Web Worker (globalThis === self)
+ * - Node.js
+ * - SpiderMonkey (mozjs)
+ * - Rhino 7.14+
+ * - any other embedded JS engine
+ *
+ * CommonJS module.exports (commonjs2):
+ * - Node.js
+ *
+ * CommonJS exports (commonjs, https://wiki.commonjs.org/wiki/Modules):
+ * - Rhino
+ */
 export default function exportQUnit (QUnit) {
-  let exportedModule = false;
-
   if (window && document) {
     // QUnit may be defined when it is preconfigured but then only QUnit and QUnit.config may be defined.
-    if (window.QUnit && window.QUnit.version) {
+    if (globalThis.QUnit && globalThis.QUnit.version) {
       throw new Error('QUnit has already been defined.');
     }
-
-    window.QUnit = QUnit;
-
-    exportedModule = true;
   }
 
   // For Node.js
@@ -21,20 +32,20 @@ export default function exportQUnit (QUnit) {
 
     // For consistency with CommonJS environments' exports
     module.exports.QUnit = QUnit;
-
-    exportedModule = true;
   }
 
   // For CommonJS with exports, but without module.exports, like Rhino
   if (typeof exports !== 'undefined' && exports) {
     exports.QUnit = QUnit;
-
-    exportedModule = true;
   }
 
-  // For other environments, including Web Workers (globalThis === self),
-  // SpiderMonkey (mozjs), and other embedded JavaScript engines
-  if (!exportedModule) {
+  // Ensure the global is available in all environments.
+  //
+  // For backward compatibility, we only enforce load-once in browsers above.
+  // In other environments QUnit is accessible via import/require() and may
+  // load multiple times. Callers may decide whether their secondary instance
+  // should be global or not.
+  if (!globalThis.QUnit || !globalThis.QUnit.version) {
     globalThis.QUnit = QUnit;
   }
 }
diff --git a/test/benchmark/micro.js b/test/benchmark/micro.js
index da0014964..0d7949fea 100644
--- a/test/benchmark/micro.js
+++ b/test/benchmark/micro.js
@@ -1,5 +1,5 @@
 /* eslint-env node */
 
-global.QUnit = require('qunit');
+require('qunit');
 require('./micro-fixture.js');
 require('./micro-bench.js');
diff --git a/test/cli/fixtures/inception.js b/test/cli/fixtures/inception.js
index 125117fab..8eeae9825 100644
--- a/test/cli/fixtures/inception.js
+++ b/test/cli/fixtures/inception.js
@@ -1,7 +1,7 @@
-const outerQUnit = global.QUnit;
-delete global.QUnit;
+const outerQUnit = globalThis.QUnit;
+delete globalThis.QUnit;
 const myQUnit = require('../../../src/cli/require-qunit')();
-global.QUnit = outerQUnit;
+globalThis.QUnit = outerQUnit;
 
 const data = [];
 myQUnit.on('runStart', function () {