diff --git a/src/ble-pybricks-service/actions.ts b/src/ble-pybricks-service/actions.ts
index cda33a01d..9961bd3df 100644
--- a/src/ble-pybricks-service/actions.ts
+++ b/src/ble-pybricks-service/actions.ts
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2021-2024 The Pybricks Authors
+// Copyright (c) 2021-2025 The Pybricks Authors
 //
 // Actions for Bluetooth Low Energy Pybricks service
 
@@ -81,15 +81,17 @@ export const sendLegacyStartReplCommand = createAction((id: number) => ({
 /**
  * Action that requests a start user program to be sent.
  * @param id Unique identifier for this transaction.
- * @param slot The slot number of the user program to start.
+ * @param progId The program ID number of the user program to start.
  *
  * @since Pybricks Profile v1.4.0
  */
-export const sendStartUserProgramCommand = createAction((id: number, slot: number) => ({
-    type: 'blePybricksServiceCommand.action.sendStartUserProgram',
-    id,
-    slot,
-}));
+export const sendStartUserProgramCommand = createAction(
+    (id: number, progId: number) => ({
+        type: 'blePybricksServiceCommand.action.sendStartUserProgram',
+        id,
+        progId,
+    }),
+);
 
 /**
  * Action that requests to write user program metadata.
@@ -180,13 +182,15 @@ export const didFailToSendCommand = createAction((id: number, error: Error) => (
 /**
  * Action that represents a status report event received from the hub.
  * @param statusFlags The status flags.
- * @param slot The slot number of the user program that is running.
+ * @param progId The ID number of the user program that is running.
+ * @param selectedSlot The currently selected slot on the hub.
  */
 export const didReceiveStatusReport = createAction(
-    (statusFlags: number, slot: number) => ({
+    (statusFlags: number, runningProgId: number, selectedSlot: number) => ({
         type: 'blePybricksServiceEvent.action.didReceiveStatusReport',
         statusFlags,
-        slot,
+        runningProgId,
+        selectedSlot,
     }),
 );
 
@@ -224,13 +228,17 @@ export const eventProtocolError = createAction((error: Error) => ({
 /**
  * Action that is called when the Pybricks Hub Capbailities characteristic
  * is read.
+ *
+ * @since Pybricks Profile v1.2.0
+ * @changed numOfSlots added in v.1.5.0
  */
 export const blePybricksServiceDidReceiveHubCapabilities = createAction(
-    (maxWriteSize: number, flags: number, maxUserProgramSize: number) => ({
+    (maxWriteSize: number, flags: number, maxUserProgramSize: number, numOfSlots) => ({
         type: 'blePybricksServiceEvent.action.didReceiveHubCapabilities',
         maxWriteSize,
         flags,
         maxUserProgramSize,
+        numOfSlots,
     }),
 );
 
diff --git a/src/ble-pybricks-service/protocol.ts b/src/ble-pybricks-service/protocol.ts
index 773aa25a2..63334d872 100644
--- a/src/ble-pybricks-service/protocol.ts
+++ b/src/ble-pybricks-service/protocol.ts
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2020-2024 The Pybricks Authors
+// Copyright (c) 2020-2025 The Pybricks Authors
 //
 // Definitions related to the Pybricks Bluetooth low energy GATT service.
 
@@ -112,17 +112,17 @@ export function createStopUserProgramCommand(): Uint8Array {
  * Creates a {@link CommandType.StartUserProgram} message.
  *
  * Parameters:
- * - slot: Program identifier (one byte). Slots 0--127 are reserved for
+ * - progId: Program identifier (one byte). Slots 0--127 are reserved for
  *   downloaded user programs. Slots 128--255 are for builtin user programs.
  *
  * @since Pybricks Profile v1.4.0
  */
 export function createStartUserProgramCommand(
-    slot: number | BuiltinProgramId,
+    progId: number | BuiltinProgramId,
 ): Uint8Array {
     const msg = new Uint8Array(2);
     msg[0] = CommandType.StartUserProgram;
-    msg[1] = slot;
+    msg[1] = progId;
     return msg;
 }
 
@@ -303,15 +303,23 @@ export function getEventType(msg: DataView): EventType {
 /**
  * Parses the payload of a status report message.
  * @param msg The raw message data.
- * @returns The status as bit flags and the slot number of the running program.
+ * @returns The status as bit flags, the program ID number of the running program,
+ * and the currently selected slot.
  *
- * @since Pybricks Profile v1.0.0 - changed in v1.4.0
+ * @since Pybricks Profile v1.0.0
+ * @changed runningProgId added in v1.4.0
+ * @changed selectedSlot added in v1.5.0
  */
-export function parseStatusReport(msg: DataView): { flags: number; slot: number } {
+export function parseStatusReport(msg: DataView): {
+    flags: number;
+    runningProgId: number;
+    selectedSlot: number;
+} {
     assert(msg.getUint8(0) === EventType.StatusReport, 'expecting status report event');
     return {
         flags: msg.getUint32(1, true),
-        slot: msg.byteLength > 5 ? msg.getUint8(5) : 0,
+        runningProgId: msg.byteLength > 5 ? msg.getUint8(5) : 0,
+        selectedSlot: msg.byteLength > 6 ? msg.getUint8(6) : 0,
     };
 }
 
diff --git a/src/ble-pybricks-service/sagas.test.ts b/src/ble-pybricks-service/sagas.test.ts
index 698bd8ae5..69562e43b 100644
--- a/src/ble-pybricks-service/sagas.test.ts
+++ b/src/ble-pybricks-service/sagas.test.ts
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2021-2024 The Pybricks Authors
+// Copyright (c) 2021-2025 The Pybricks Authors
 
 import { AsyncSaga } from '../../test';
 import {
@@ -35,11 +35,11 @@ describe('command encoder', () => {
             ],
         ],
         [
-            'start user program with slot',
+            'start user program with program id',
             sendStartUserProgramCommand(0, 0x2a),
             [
                 0x01, // start user program command
-                0x2a, // program slot
+                0x2a, // program ID
             ],
         ],
         [
@@ -174,7 +174,7 @@ describe('command encoder', () => {
 describe('event decoder', () => {
     test.each([
         [
-            'legacy status report',
+            'v1.3 status report',
             [
                 0x00, // status report event
                 0x01, // flags count LSB
@@ -182,7 +182,19 @@ describe('event decoder', () => {
                 0x00, // .
                 0x00, // flags count MSB
             ],
-            didReceiveStatusReport(0x00000001, 0),
+            didReceiveStatusReport(0x00000001, 0, 0),
+        ],
+        [
+            'v1.4 status report',
+            [
+                0x00, // status report event
+                0x01, // flags count LSB
+                0x00, // .
+                0x00, // .
+                0x00, // flags count MSB
+                0x80, // program ID
+            ],
+            didReceiveStatusReport(0x00000001, BuiltinProgramId.REPL, 0),
         ],
         [
             'status report',
@@ -192,9 +204,10 @@ describe('event decoder', () => {
                 0x00, // .
                 0x00, // .
                 0x00, // flags count MSB
-                0x80, // slot
+                0x80, // program ID
+                0x02, // selected slot
             ],
-            didReceiveStatusReport(0x00000001, BuiltinProgramId.REPL),
+            didReceiveStatusReport(0x00000001, BuiltinProgramId.REPL, 2),
         ],
         [
             'write stdout',
diff --git a/src/ble-pybricks-service/sagas.ts b/src/ble-pybricks-service/sagas.ts
index 7fffdc5da..8ddc3b808 100644
--- a/src/ble-pybricks-service/sagas.ts
+++ b/src/ble-pybricks-service/sagas.ts
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2021-2024 The Pybricks Authors
+// Copyright (c) 2021-2025 The Pybricks Authors
 //
 // Handles Pybricks protocol.
 
@@ -75,7 +75,7 @@ function* encodeRequest(): Generator {
             yield* put(writeCommand(action.id, createLegacyStartReplCommand()));
         } else if (sendStartUserProgramCommand.matches(action)) {
             yield* put(
-                writeCommand(action.id, createStartUserProgramCommand(action.slot)),
+                writeCommand(action.id, createStartUserProgramCommand(action.progId)),
             );
         } else if (sendWriteUserProgramMetaCommand.matches(action)) {
             yield* put(
@@ -127,7 +127,13 @@ function* decodeResponse(action: ReturnType<typeof didNotifyEvent>): Generator {
         switch (responseType) {
             case EventType.StatusReport: {
                 const status = parseStatusReport(action.value);
-                yield* put(didReceiveStatusReport(status.flags, status.slot));
+                yield* put(
+                    didReceiveStatusReport(
+                        status.flags,
+                        status.runningProgId,
+                        status.selectedSlot,
+                    ),
+                );
                 break;
             }
             case EventType.WriteStdout:
diff --git a/src/ble/reducers.test.ts b/src/ble/reducers.test.ts
index 716688b73..deba2a9a1 100644
--- a/src/ble/reducers.test.ts
+++ b/src/ble/reducers.test.ts
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2021-2024 The Pybricks Authors
+// Copyright (c) 2021-2025 The Pybricks Authors
 
 import { AnyAction } from 'redux';
 import {
@@ -130,14 +130,18 @@ test('deviceLowBatteryWarning', () => {
     expect(
         reducers(
             { deviceLowBatteryWarning: false } as State,
-            didReceiveStatusReport(statusToFlag(Status.BatteryLowVoltageWarning), 0),
+            didReceiveStatusReport(statusToFlag(Status.BatteryLowVoltageWarning), 0, 0),
         ).deviceLowBatteryWarning,
     ).toBeTruthy();
 
     expect(
         reducers(
             { deviceLowBatteryWarning: true } as State,
-            didReceiveStatusReport(~statusToFlag(Status.BatteryLowVoltageWarning), 0),
+            didReceiveStatusReport(
+                ~statusToFlag(Status.BatteryLowVoltageWarning),
+                0,
+                0,
+            ),
         ).deviceLowBatteryWarning,
     ).toBeFalsy();
 
diff --git a/src/ble/sagas.test.ts b/src/ble/sagas.test.ts
index 1062e4bc7..25c497437 100644
--- a/src/ble/sagas.test.ts
+++ b/src/ble/sagas.test.ts
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2022-2023 The Pybricks Authors
+// Copyright (c) 2022-2025 The Pybricks Authors
 
 import { MockProxy, mock } from 'jest-mock-extended';
 import { AsyncSaga } from '../../test';
@@ -114,7 +114,7 @@ function createMocks(): Mocks {
     hubCapabilitiesChar.readValue.mockResolvedValue(
         new DataView(
             new Uint8Array([
-                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             ]).buffer,
         ),
     );
@@ -459,7 +459,7 @@ describe('connect action is dispatched', () => {
             );
 
             await expect(saga.take()).resolves.toEqual(
-                blePybricksServiceDidReceiveHubCapabilities(0, 0, 0),
+                blePybricksServiceDidReceiveHubCapabilities(0, 0, 0, 0),
             );
 
             await expect(saga.take()).resolves.toEqual(
diff --git a/src/ble/sagas.ts b/src/ble/sagas.ts
index be3fb191d..3c5ae49d1 100644
--- a/src/ble/sagas.ts
+++ b/src/ble/sagas.ts
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2020-2023 The Pybricks Authors
+// Copyright (c) 2020-2025 The Pybricks Authors
 //
 // Manages connection to a Bluetooth Low Energy device running Pybricks firmware.
 
@@ -73,7 +73,7 @@ import {
 import { BleConnectionState } from './reducers';
 
 /** The version of the Pybricks Profile version currently implemented by this file. */
-export const supportedPybricksProfileVersion = '1.4.0';
+export const supportedPybricksProfileVersion = '1.5.0';
 
 const decoder = new TextDecoder();
 
@@ -378,11 +378,20 @@ function* handleBleConnectPybricks(): Generator {
             const flags = hubCapabilitiesValue.getUint32(2, true);
             const maxUserProgramSize = hubCapabilitiesValue.getUint32(6, true);
 
+            const numOfSlots = (() => {
+                if (semver.satisfies(softwareRevision, '^1.5.0')) {
+                    return hubCapabilitiesValue.getUint8(10);
+                }
+
+                return 0;
+            })();
+
             yield* put(
                 blePybricksServiceDidReceiveHubCapabilities(
                     maxWriteSize,
                     flags,
                     maxUserProgramSize,
+                    numOfSlots,
                 ),
             );
         } else {
diff --git a/src/hub/reducers.test.ts b/src/hub/reducers.test.ts
index 04a691483..7e7bbf837 100644
--- a/src/hub/reducers.test.ts
+++ b/src/hub/reducers.test.ts
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2021-2024 The Pybricks Authors
+// Copyright (c) 2021-2025 The Pybricks Authors
 
 import { AnyAction } from 'redux';
 import {
@@ -44,8 +44,10 @@ test('initial state', () => {
           "hasRepl": false,
           "maxBleWriteSize": 0,
           "maxUserProgramSize": 0,
+          "numOfSlots": 0,
           "preferredFileFormat": null,
           "runtime": "hub.runtime.disconnected",
+          "selectedSlot": 0,
           "useLegacyDownload": false,
           "useLegacyStartUserProgram": false,
           "useLegacyStdio": false,
@@ -158,7 +160,7 @@ describe('runtime', () => {
         expect(
             reducers(
                 { runtime: HubRuntimeState.Disconnected } as State,
-                didReceiveStatusReport(statusToFlag(Status.UserProgramRunning), 0),
+                didReceiveStatusReport(statusToFlag(Status.UserProgramRunning), 0, 0),
             ).runtime,
         ).toBe(HubRuntimeState.Disconnected);
 
@@ -166,7 +168,7 @@ describe('runtime', () => {
         expect(
             reducers(
                 { runtime: HubRuntimeState.Loading } as State,
-                didReceiveStatusReport(statusToFlag(Status.UserProgramRunning), 0),
+                didReceiveStatusReport(statusToFlag(Status.UserProgramRunning), 0, 0),
             ).runtime,
         ).toBe(HubRuntimeState.Loading);
 
@@ -174,7 +176,7 @@ describe('runtime', () => {
         expect(
             reducers(
                 { runtime: HubRuntimeState.Unknown } as State,
-                didReceiveStatusReport(statusToFlag(Status.UserProgramRunning), 0),
+                didReceiveStatusReport(statusToFlag(Status.UserProgramRunning), 0, 0),
             ).runtime,
         ).toBe(HubRuntimeState.Running);
 
@@ -182,7 +184,7 @@ describe('runtime', () => {
         expect(
             reducers(
                 { runtime: HubRuntimeState.Unknown } as State,
-                didReceiveStatusReport(0, 0),
+                didReceiveStatusReport(0, 0, 0),
             ).runtime,
         ).toBe(HubRuntimeState.Idle);
 
@@ -190,7 +192,7 @@ describe('runtime', () => {
         expect(
             reducers(
                 { runtime: HubRuntimeState.Running } as State,
-                didReceiveStatusReport(0, 0),
+                didReceiveStatusReport(0, 0, 0),
             ).runtime,
         ).toBe(HubRuntimeState.Idle);
 
@@ -198,7 +200,7 @@ describe('runtime', () => {
         expect(
             reducers(
                 { runtime: HubRuntimeState.StartingRepl } as State,
-                didReceiveStatusReport(0, 0),
+                didReceiveStatusReport(0, 0, 0),
             ).runtime,
         ).toBe(HubRuntimeState.StartingRepl);
 
@@ -206,7 +208,7 @@ describe('runtime', () => {
         expect(
             reducers(
                 { runtime: HubRuntimeState.StoppingUserProgram } as State,
-                didReceiveStatusReport(0, 0),
+                didReceiveStatusReport(0, 0, 0),
             ).runtime,
         ).toBe(HubRuntimeState.StoppingUserProgram);
     });
@@ -301,7 +303,7 @@ describe('maxBleWriteSize', () => {
         expect(
             reducers(
                 { maxBleWriteSize: 0 } as State,
-                blePybricksServiceDidReceiveHubCapabilities(size, 0, 100),
+                blePybricksServiceDidReceiveHubCapabilities(size, 0, 100, 0),
             ).maxBleWriteSize,
         ).toBe(size);
     });
@@ -312,7 +314,7 @@ describe('maxUserProgramSize', () => {
         expect(
             reducers(
                 { maxUserProgramSize: 0 } as State,
-                blePybricksServiceDidReceiveHubCapabilities(23, 0, size),
+                blePybricksServiceDidReceiveHubCapabilities(23, 0, size, 0),
             ).maxUserProgramSize,
         ).toBe(size);
     });
@@ -340,7 +342,7 @@ describe('hasRepl', () => {
             expect(
                 reducers(
                     { hasRepl: true } as State,
-                    blePybricksServiceDidReceiveHubCapabilities(23, flag, 100),
+                    blePybricksServiceDidReceiveHubCapabilities(23, flag, 100, 0),
                 ).hasRepl,
             ).toBe(Boolean(flag & HubCapabilityFlag.HasRepl));
         },
@@ -374,6 +376,7 @@ describe('preferredFileFormat', () => {
                     23,
                     HubCapabilityFlag.UserProgramMultiMpy6,
                     100,
+                    0,
                 ),
             ).preferredFileFormat,
         ).toBe(FileFormat.MultiMpy6);
@@ -383,7 +386,7 @@ describe('preferredFileFormat', () => {
         expect(
             reducers(
                 { preferredFileFormat: FileFormat.MultiMpy6 } as State,
-                blePybricksServiceDidReceiveHubCapabilities(23, 0, 100),
+                blePybricksServiceDidReceiveHubCapabilities(23, 0, 100, 0),
             ).preferredFileFormat,
         ).toBeNull();
     });
@@ -403,7 +406,7 @@ describe('useLegacyDownload', () => {
         expect(
             reducers(
                 { useLegacyDownload: true } as State,
-                blePybricksServiceDidReceiveHubCapabilities(23, 0, 100),
+                blePybricksServiceDidReceiveHubCapabilities(23, 0, 100, 0),
             ).useLegacyDownload,
         ).toBeFalsy();
     });
diff --git a/src/hub/reducers.ts b/src/hub/reducers.ts
index 28a5c672b..73824d238 100644
--- a/src/hub/reducers.ts
+++ b/src/hub/reducers.ts
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2020-2024 The Pybricks Authors
+// Copyright (c) 2020-2025 The Pybricks Authors
 
 import { Reducer, combineReducers } from 'redux';
 import * as semver from 'semver';
@@ -275,6 +275,28 @@ const useLegacyStartUserProgram: Reducer<boolean> = (state = false, action) => {
     return state;
 };
 
+/*
+ * Returns number of available slots or 0 for slots not supported.
+ */
+const numOfSlots: Reducer<number> = (state = 0, action) => {
+    if (blePybricksServiceDidReceiveHubCapabilities.matches(action)) {
+        return action.numOfSlots;
+    }
+
+    return state;
+};
+
+/*
+ * Returns the currently selected slot on a connected hub.
+ */
+const selectedSlot: Reducer<number> = (state = 0, action) => {
+    if (didReceiveStatusReport.matches(action)) {
+        return action.selectedSlot;
+    }
+
+    return state;
+};
+
 export default combineReducers({
     runtime,
     downloadProgress,
@@ -285,4 +307,6 @@ export default combineReducers({
     useLegacyDownload,
     useLegacyStdio,
     useLegacyStartUserProgram,
+    numOfSlots,
+    selectedSlot,
 });
diff --git a/src/toolbar/buttons/run/RunButton.tsx b/src/toolbar/buttons/run/RunButton.tsx
index a7ce63c0f..226e1d579 100644
--- a/src/toolbar/buttons/run/RunButton.tsx
+++ b/src/toolbar/buttons/run/RunButton.tsx
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2020-2024 The Pybricks Authors
+// Copyright (c) 2020-2025 The Pybricks Authors
 
 import React from 'react';
 import { useDispatch } from 'react-redux';
@@ -19,6 +19,7 @@ const RunButton: React.FunctionComponent<RunButtonProps> = ({ id }) => {
         runtime,
         useLegacyDownload,
         useLegacyStartUserProgram,
+        selectedSlot,
     } = useSelector((s) => s.hub);
     const activeFile = useSelector((s) => s.editor.activeFileUuid);
     const keyboardShortcut = 'F5';
@@ -48,7 +49,7 @@ const RunButton: React.FunctionComponent<RunButtonProps> = ({ id }) => {
                         preferredFileFormat,
                         useLegacyDownload,
                         useLegacyStartUserProgram,
-                        0, // No slot UI yet
+                        selectedSlot,
                     ),
                 )
             }