diff --git a/mailpoet/RoboFile.php b/mailpoet/RoboFile.php
index 70c6e4d560..7724add45a 100644
--- a/mailpoet/RoboFile.php
+++ b/mailpoet/RoboFile.php
@@ -388,7 +388,7 @@ class RoboFile extends \Robo\Tasks {
   }
 
   public function testJavascript($xmlOutputFile = null) {
-    $command = './node_modules/.bin/mocha --recursive --require tests/javascript/babel-register.js tests/javascript --extension spec.js --extension spec.ts';
+    $command = './node_modules/.bin/mocha --recursive --require tests/javascript/mocha-env.mjs  tests/javascript --extension spec.ts';
 
     if (!empty($xmlOutputFile)) {
       $command .= sprintf(
diff --git a/mailpoet/package.json b/mailpoet/package.json
index 28ae6537d5..2e923e8f26 100644
--- a/mailpoet/package.json
+++ b/mailpoet/package.json
@@ -9,7 +9,7 @@
     "scss": "sass assets/css/src/:assets/dist/css/ --style compressed",
     "stylelint": "stylelint --fix",
     "stylelint-check": "stylelint",
-    "test": "env NODE_PATH=$NODE_PATH:./assets/js/src mocha --recursive --require tests/javascript/babel-register.js  tests/javascript --extension spec.js --extension spec.ts",
+    "test": "env NODE_PATH=$NODE_PATH:./assets/js/src mocha --recursive --require tests/javascript/mocha-env.mjs  tests/javascript --extension spec.ts",
     "check-types": "NODE_OPTIONS=--max_old_space_size=2048 tsc --noEmit",
     "storybook": "start-storybook -s ./ -p 8083",
     "build-storybook": "build-storybook",
diff --git a/mailpoet/tests/javascript/babel-register.js b/mailpoet/tests/javascript/babel-register.js
deleted file mode 100644
index 7610e62842..0000000000
--- a/mailpoet/tests/javascript/babel-register.js
+++ /dev/null
@@ -1 +0,0 @@
-require('@babel/register')({ extensions: ['.js', '.jsx', '.ts', '.tsx'] });
diff --git a/mailpoet/tests/javascript/form-editor/store/blocks-to-form-body.spec.ts b/mailpoet/tests/javascript/form-editor/store/blocks-to-form-body.spec.ts
index 6c4d1feaa2..c6ea7ad9df 100644
--- a/mailpoet/tests/javascript/form-editor/store/blocks-to-form-body.spec.ts
+++ b/mailpoet/tests/javascript/form-editor/store/blocks-to-form-body.spec.ts
@@ -1,4 +1,3 @@
-import { expect } from 'chai';
 import { partial, isEmpty, isUndefined } from 'lodash';
 import { blocksToFormBodyFactory } from '../../../../assets/js/src/form-editor/store/blocks-to-form-body';
 import {
diff --git a/mailpoet/tests/javascript/form-editor/store/form-body-to-blocks.spec.ts b/mailpoet/tests/javascript/form-editor/store/form-body-to-blocks.spec.ts
index 9354b9f9ce..836c038c6f 100644
--- a/mailpoet/tests/javascript/form-editor/store/form-body-to-blocks.spec.ts
+++ b/mailpoet/tests/javascript/form-editor/store/form-body-to-blocks.spec.ts
@@ -1,4 +1,3 @@
-import { expect } from 'chai';
 import { partial, isEmpty, isUndefined } from 'lodash';
 import { formBodyToBlocksFactory } from '../../../../assets/js/src/form-editor/store/form-body-to-blocks.jsx';
 
diff --git a/mailpoet/tests/javascript/form-editor/store/form-validator.spec.ts b/mailpoet/tests/javascript/form-editor/store/form-validator.spec.ts
index cf83d83255..33755930e1 100644
--- a/mailpoet/tests/javascript/form-editor/store/form-validator.spec.ts
+++ b/mailpoet/tests/javascript/form-editor/store/form-validator.spec.ts
@@ -1,4 +1,3 @@
-import { expect } from 'chai';
 import { isEmpty } from 'lodash';
 import { validateForm as validate } from '../../../../assets/js/src/form-editor/store/form-validator.jsx';
 
diff --git a/mailpoet/tests/javascript/form-editor/store/map-form-data-after-loading.spec.ts b/mailpoet/tests/javascript/form-editor/store/map-form-data-after-loading.spec.ts
index e983568037..20b66500f1 100644
--- a/mailpoet/tests/javascript/form-editor/store/map-form-data-after-loading.spec.ts
+++ b/mailpoet/tests/javascript/form-editor/store/map-form-data-after-loading.spec.ts
@@ -1,4 +1,3 @@
-import { expect } from 'chai';
 import { mapFormDataAfterLoading as map } from '../../../../assets/js/src/form-editor/store/map-form-data-after-loading.jsx';
 
 const data = {
diff --git a/mailpoet/tests/javascript/form-editor/store/map-form-data-before-saving.spec.ts b/mailpoet/tests/javascript/form-editor/store/map-form-data-before-saving.spec.ts
index 3f1813066e..c028c194ca 100644
--- a/mailpoet/tests/javascript/form-editor/store/map-form-data-before-saving.spec.ts
+++ b/mailpoet/tests/javascript/form-editor/store/map-form-data-before-saving.spec.ts
@@ -1,4 +1,3 @@
-import { expect } from 'chai';
 import { mapFormDataBeforeSaving as map } from '../../../../assets/js/src/form-editor/store/map-form-data-before-saving.jsx';
 
 const data = {
diff --git a/mailpoet/tests/javascript/form-editor/store/reducers/create-custom-field-started.spec.ts b/mailpoet/tests/javascript/form-editor/store/reducers/create-custom-field-started.spec.ts
index 1f03189fea..d27d5b0786 100644
--- a/mailpoet/tests/javascript/form-editor/store/reducers/create-custom-field-started.spec.ts
+++ b/mailpoet/tests/javascript/form-editor/store/reducers/create-custom-field-started.spec.ts
@@ -1,4 +1,3 @@
-import { expect } from 'chai';
 import { createCustomFieldStartedFactory } from '../../../../../assets/js/src/form-editor/store/reducers/create-custom-field-started';
 import { CustomFieldStartedAction } from '../../../../../assets/js/src/form-editor/store/actions-types';
 import { createCustomFieldMock, createStateMock } from '../mocks/partial-mocks';
diff --git a/mailpoet/tests/javascript/form-editor/store/reducers/history-record.spec.ts b/mailpoet/tests/javascript/form-editor/store/reducers/history-record.spec.ts
index b6effd1fe0..395a0edb95 100644
--- a/mailpoet/tests/javascript/form-editor/store/reducers/history-record.spec.ts
+++ b/mailpoet/tests/javascript/form-editor/store/reducers/history-record.spec.ts
@@ -1,4 +1,3 @@
-import { expect } from 'chai';
 import {
   createHistoryRecord,
   historyRedo,
diff --git a/mailpoet/tests/javascript/form-editor/store/reducers/save-form-started.spec.ts b/mailpoet/tests/javascript/form-editor/store/reducers/save-form-started.spec.ts
index 647ca4cebe..5ab064d2ec 100644
--- a/mailpoet/tests/javascript/form-editor/store/reducers/save-form-started.spec.ts
+++ b/mailpoet/tests/javascript/form-editor/store/reducers/save-form-started.spec.ts
@@ -1,4 +1,3 @@
-import { expect } from 'chai';
 import { identity } from 'lodash';
 import { saveFormStartedFactory } from '../../../../../assets/js/src/form-editor/store/reducers/save-form-started';
 import { createStateMock } from '../mocks/partial-mocks';
diff --git a/mailpoet/tests/javascript/form-editor/store/reducers/toggle-sidebar-panel.spec.ts b/mailpoet/tests/javascript/form-editor/store/reducers/toggle-sidebar-panel.spec.ts
index 71a4dfdfb7..1fea1c2093 100644
--- a/mailpoet/tests/javascript/form-editor/store/reducers/toggle-sidebar-panel.spec.ts
+++ b/mailpoet/tests/javascript/form-editor/store/reducers/toggle-sidebar-panel.spec.ts
@@ -1,4 +1,3 @@
-import { expect } from 'chai';
 import { toggleSidebarPanel as reducer } from '../../../../../assets/js/src/form-editor/store/reducers/toggle-sidebar-panel';
 import { ToggleSidebarPanelAction } from '../../../../../assets/js/src/form-editor/store/actions-types';
 import { createStateMock } from '../mocks/partial-mocks';
diff --git a/mailpoet/tests/javascript/form-editor/store/selectors.spec.ts b/mailpoet/tests/javascript/form-editor/store/selectors.spec.ts
index a04ba67822..808a32b3a3 100644
--- a/mailpoet/tests/javascript/form-editor/store/selectors.spec.ts
+++ b/mailpoet/tests/javascript/form-editor/store/selectors.spec.ts
@@ -1,4 +1,3 @@
-import { expect } from 'chai';
 import { selectors } from '../../../../assets/js/src/form-editor/store/selectors';
 import {
   createBlocksMock,
diff --git a/mailpoet/tests/javascript/form-editor/store/server-value-as-num.spec.ts b/mailpoet/tests/javascript/form-editor/store/server-value-as-num.spec.ts
index e55cdb92f5..c030948fd9 100644
--- a/mailpoet/tests/javascript/form-editor/store/server-value-as-num.spec.ts
+++ b/mailpoet/tests/javascript/form-editor/store/server-value-as-num.spec.ts
@@ -1,5 +1,3 @@
-import { expect } from 'chai';
-
 import { asNum } from '../../../../assets/js/src/form-editor/store/server-value-as-num';
 
 describe('Server value as num', () => {
diff --git a/mailpoet/tests/javascript/global.d.ts b/mailpoet/tests/javascript/global.d.ts
new file mode 100644
index 0000000000..504992f67a
--- /dev/null
+++ b/mailpoet/tests/javascript/global.d.ts
@@ -0,0 +1,5 @@
+import type * as chai from 'chai';
+
+declare global {
+  const expect: typeof chai.expect;
+}
diff --git a/mailpoet/tests/javascript/mocha-env.mjs b/mailpoet/tests/javascript/mocha-env.mjs
new file mode 100644
index 0000000000..791898bb97
--- /dev/null
+++ b/mailpoet/tests/javascript/mocha-env.mjs
@@ -0,0 +1,9 @@
+import * as chai from 'chai';
+import register from '@babel/register';
+
+// Register Babel to transpile our tests
+register({ extensions: ['.js', '.jsx', '.ts', '.tsx'] });
+
+// Set up chai.expect globally due issues with ES modules
+// See https://github.com/chaijs/chai/issues/1568
+global.expect = chai.expect;
diff --git a/mailpoet/tests/javascript/utilities/date.spec.ts b/mailpoet/tests/javascript/utilities/date.spec.ts
index 6cda193cd4..a8f18dc5ee 100644
--- a/mailpoet/tests/javascript/utilities/date.spec.ts
+++ b/mailpoet/tests/javascript/utilities/date.spec.ts
@@ -1,4 +1,3 @@
-import { expect } from 'chai';
 import moment, { Moment } from 'moment';
 import { MailPoetDate } from '../../../assets/js/src/date';