diff --git a/CHANGELOG.md b/CHANGELOG.md
index 37311cf7..08821870 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,10 @@
 
 ## [Unreleased]
 
+### Fixed
+- Fixed starting DFU flash while another was still in progress ([support#1146]).
+
+[support#1146]: https://github.com/pybricks/support/issues/1146
 ## [2.2.0-beta.8] - 2023-07-07
 
 ### Changed
diff --git a/src/firmware/installPybricksDialog/InstallPybricksDialog.tsx b/src/firmware/installPybricksDialog/InstallPybricksDialog.tsx
index 355b0977..b5643ab6 100644
--- a/src/firmware/installPybricksDialog/InstallPybricksDialog.tsx
+++ b/src/firmware/installPybricksDialog/InstallPybricksDialog.tsx
@@ -450,6 +450,11 @@ const BootloaderModePanel: React.FunctionComponent<BootloaderModePanelProps> = (
 
 export const InstallPybricksDialog: React.FunctionComponent = () => {
     const { isOpen } = useSelector((s) => s.firmware.installPybricksDialog);
+    const inProgress = useSelector(
+        (s) =>
+            s.firmware.isFirmwareFlashUsbDfuInProgress ||
+            s.firmware.isFirmwareRestoreOfficialDfuInProgress,
+    );
     const dispatch = useDispatch();
     const [hubName, setHubName] = useState('');
     const [licenseAccepted, setLicenseAccepted] = useState(false);
@@ -476,6 +481,7 @@ export const InstallPybricksDialog: React.FunctionComponent = () => {
             nextButtonProps={{ text: i18n.translate('nextButton.label') }}
             finalButtonProps={{
                 text: i18n.translate('flashFirmwareButton.label'),
+                disabled: inProgress,
                 onClick: () =>
                     dispatch(
                         firmwareInstallPybricksDialogAccept(
diff --git a/src/firmware/reducers.test.ts b/src/firmware/reducers.test.ts
index 76ccc47a..1e93e6c3 100644
--- a/src/firmware/reducers.test.ts
+++ b/src/firmware/reducers.test.ts
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2021-2022 The Pybricks Authors
+// Copyright (c) 2021-2023 The Pybricks Authors
 
 import { AnyAction } from 'redux';
 import {
@@ -23,6 +23,8 @@ test('initial state', () => {
           "installPybricksDialog": {
             "isOpen": false,
           },
+          "isFirmwareFlashUsbDfuInProgress": false,
+          "isFirmwareRestoreOfficialDfuInProgress": false,
           "progress": null,
           "restoreOfficialDialog": {
             "isOpen": false,
diff --git a/src/firmware/reducers.ts b/src/firmware/reducers.ts
index 323dcf15..fd73fb65 100644
--- a/src/firmware/reducers.ts
+++ b/src/firmware/reducers.ts
@@ -1,8 +1,19 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2021-2022 The Pybricks Authors
+// Copyright (c) 2021-2023 The Pybricks Authors
 
 import { Reducer, combineReducers } from 'redux';
-import { didFailToFinish, didFinish, didProgress, didStart } from './actions';
+import {
+    didFailToFinish,
+    didFinish,
+    didProgress,
+    didStart,
+    firmwareDidFailToFlashUsbDfu,
+    firmwareDidFailToRestoreOfficialDfu,
+    firmwareDidFlashUsbDfu,
+    firmwareDidRestoreOfficialDfu,
+    firmwareFlashUsbDfu,
+    firmwareRestoreOfficialDfu,
+} from './actions';
 import dfuWindowsDriverInstallDialog from './dfuWindowsDriverInstallDialog/reducers';
 import installPybricksDialog from './installPybricksDialog/reducers';
 import restoreOfficialDialog from './restoreOfficialDialog/reducers';
@@ -31,10 +42,47 @@ const progress: Reducer<number | null> = (state = null, action) => {
     return state;
 };
 
+const isFirmwareFlashUsbDfuInProgress: Reducer<boolean> = (state = false, action) => {
+    if (firmwareFlashUsbDfu.matches(action)) {
+        return true;
+    }
+
+    if (firmwareDidFlashUsbDfu.matches(action)) {
+        return false;
+    }
+
+    if (firmwareDidFailToFlashUsbDfu.matches(action)) {
+        return false;
+    }
+
+    return state;
+};
+
+const isFirmwareRestoreOfficialDfuInProgress: Reducer<boolean> = (
+    state = false,
+    action,
+) => {
+    if (firmwareRestoreOfficialDfu.matches(action)) {
+        return true;
+    }
+
+    if (firmwareDidRestoreOfficialDfu.matches(action)) {
+        return false;
+    }
+
+    if (firmwareDidFailToRestoreOfficialDfu.matches(action)) {
+        return false;
+    }
+
+    return state;
+};
+
 export default combineReducers({
     dfuWindowsDriverInstallDialog,
     installPybricksDialog,
     restoreOfficialDialog,
     flashing,
     progress,
+    isFirmwareFlashUsbDfuInProgress,
+    isFirmwareRestoreOfficialDfuInProgress,
 });
diff --git a/src/firmware/restoreOfficialDialog/RestoreOfficialDialog.tsx b/src/firmware/restoreOfficialDialog/RestoreOfficialDialog.tsx
index 64cb9cb3..cd048355 100644
--- a/src/firmware/restoreOfficialDialog/RestoreOfficialDialog.tsx
+++ b/src/firmware/restoreOfficialDialog/RestoreOfficialDialog.tsx
@@ -9,7 +9,7 @@ import {
     MultistepDialog,
 } from '@blueprintjs/core';
 import classNames from 'classnames';
-import React from 'react';
+import React, { useCallback } from 'react';
 import { useDispatch } from 'react-redux';
 import {
     legoEducationSpikeRegisteredTrademark,
@@ -46,6 +46,15 @@ const RestoreFirmwarePanel: React.FunctionComponent = () => {
     const [hubType] = useHubPickerSelectedHub();
     const dispatch = useDispatch();
     const i18n = useI18n();
+    const inProgress = useSelector(
+        (s) =>
+            s.firmware.isFirmwareFlashUsbDfuInProgress ||
+            s.firmware.isFirmwareRestoreOfficialDfuInProgress,
+    );
+
+    const handleRestoreButtonClick = useCallback(() => {
+        dispatch(firmwareRestoreOfficialDfu(hubType));
+    }, [dispatch, hubType]);
 
     return (
         <div className={classNames(Classes.DIALOG_BODY, Classes.RUNNING_TEXT)}>
@@ -72,7 +81,8 @@ const RestoreFirmwarePanel: React.FunctionComponent = () => {
                     <div className="pb-spacer" />
                     <Button
                         intent={Intent.PRIMARY}
-                        onClick={() => dispatch(firmwareRestoreOfficialDfu(hubType))}
+                        disabled={inProgress}
+                        onClick={handleRestoreButtonClick}
                     >
                         {i18n.translate('restoreFirmwarePanel.flashButton')}
                     </Button>