diff --git a/src/app/constants.ts b/src/app/constants.ts
index d85545af..90d4addc 100644
--- a/src/app/constants.ts
+++ b/src/app/constants.ts
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2021-2022 The Pybricks Authors
+// Copyright (c) 2021-2023 The Pybricks Authors
 import docsPackage from '@pybricks/ide-docs/package.json';
 
 // Definitions for compile-time UI settings.
@@ -81,3 +81,9 @@ export const docsPathPrefix = `static/docs/v${docsPackage.version}/`;
 
 /** The index page of the docs. */
 export const docsDefaultPage = `${docsPathPrefix}index.html`;
+
+/** The ZIP file extension ('.zip') */
+export const zipFileExtension = '.zip';
+
+/** The ZIP file MIME type ('application/zip') */
+export const zipFileMimeType = 'application/zip';
diff --git a/src/explorer/sagas.ts b/src/explorer/sagas.ts
index 5d272c6e..d500c4d9 100644
--- a/src/explorer/sagas.ts
+++ b/src/explorer/sagas.ts
@@ -1,10 +1,11 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2022 The Pybricks Authors
+// Copyright (c) 2022-2023 The Pybricks Authors
 
 import { fileOpen, fileSave } from 'browser-fs-access';
 import JSZip from 'jszip';
 import { call, put, race, select, take, takeEvery } from 'typed-redux-saga/macro';
 import { alertsShowAlert } from '../alerts/actions';
+import { zipFileExtension, zipFileMimeType } from '../app/constants';
 import {
     editorActivateFile,
     editorCloseFile,
@@ -122,14 +123,14 @@ function* handleExplorerArchiveAllFiles(): Generator {
 
         const zipData = yield* call(() => zip.generateAsync({ type: 'blob' }));
 
-        const fileName = `pybricks-backup-${timestamp()}.zip`;
+        const fileName = `pybricks-backup-${timestamp()}${zipFileExtension}`;
 
         yield* call(() =>
             fileSave(zipData, {
                 id: 'pybricksCodeFileStorageArchive',
                 fileName,
-                extensions: ['.zip'],
-                mimeTypes: ['application/zip'],
+                extensions: [zipFileExtension],
+                mimeTypes: [zipFileMimeType],
                 // TODO: translate description
                 description: 'Zip Files',
             }),
diff --git a/src/firmware/installPybricksDialog/InstallPybricksDialog.tsx b/src/firmware/installPybricksDialog/InstallPybricksDialog.tsx
index 0b438d50..fb9661c5 100644
--- a/src/firmware/installPybricksDialog/InstallPybricksDialog.tsx
+++ b/src/firmware/installPybricksDialog/InstallPybricksDialog.tsx
@@ -28,7 +28,12 @@ import { useDropzone } from 'react-dropzone';
 import { useDispatch } from 'react-redux';
 import { useLocalStorage } from 'usehooks-ts';
 import { alertsShowAlert } from '../../alerts/actions';
-import { appName, legoMindstormsRegisteredTrademark } from '../../app/constants';
+import {
+    appName,
+    legoMindstormsRegisteredTrademark,
+    zipFileExtension,
+    zipFileMimeType,
+} from '../../app/constants';
 import HelpButton from '../../components/HelpButton';
 import { Hub, hubBootloaderType } from '../../components/hubPicker';
 import { HubPicker } from '../../components/hubPicker/HubPicker';
@@ -201,8 +206,8 @@ const SelectHubPanel: React.VoidFunctionComponent<SelectHubPanelProps> = ({
         try {
             const file = await fileOpen({
                 id: 'customFirmware',
-                mimeTypes: ['application/zip'],
-                extensions: ['.zip'],
+                mimeTypes: [zipFileMimeType],
+                extensions: [zipFileExtension],
                 // TODO: translate description
                 description: 'Zip Files',
                 excludeAcceptAllOption: true,
@@ -236,7 +241,7 @@ const SelectHubPanel: React.VoidFunctionComponent<SelectHubPanelProps> = ({
     );
 
     const { getRootProps, getInputProps } = useDropzone({
-        accept: { 'application/zip': ['.zip'] },
+        accept: { [zipFileMimeType]: [zipFileExtension] },
         multiple: false,
         // react-dropzone doesn't allow full control of File System API, so we
         // implement our own using browser-fs-access instead.