diff --git a/electron/ipc/handlers.ts b/electron/ipc/handlers.ts
index 958ef6d96..2be50eda2 100644
--- a/electron/ipc/handlers.ts
+++ b/electron/ipc/handlers.ts
@@ -2723,6 +2723,14 @@ export function registerIpcHandlers(
 
 			await waitForNativeMacCaptureStart(proc);
 			const captureStartedAtMs = Date.now();
+			const microphoneDefaulted =
+				request.audio.microphone.enabled && readMicrophoneDefaulted(nativeMacCaptureOutput);
+			if (microphoneDefaulted) {
+				console.warn("[native-sck] recording the default input; microphone was not resolved", {
+					deviceId: request.audio.microphone.deviceId,
+					deviceName: request.audio.microphone.deviceName,
+				});
+			}
 			nativeMacCursorOffsetMs =
 				cursorCaptureMode === "editable-overlay"
 					? Math.max(0, captureStartedAtMs - cursorStartTimeMs)
@@ -2738,6 +2746,7 @@ export function registerIpcHandlers(
 				recordingId,
 				path: outputPath,
 				helperPath,
+				microphoneDefaulted,
 			};
 		} catch (error) {
 			console.error("Failed to start native macOS recording:", error);
diff --git a/electron/native/screencapturekit/Sources/OpenScreenScreenCaptureKitHelper/ScreenCaptureRecorder.swift b/electron/native/screencapturekit/Sources/OpenScreenScreenCaptureKitHelper/ScreenCaptureRecorder.swift
index 5add8074d..aec518daf 100644
--- a/electron/native/screencapturekit/Sources/OpenScreenScreenCaptureKitHelper/ScreenCaptureRecorder.swift
+++ b/electron/native/screencapturekit/Sources/OpenScreenScreenCaptureKitHelper/ScreenCaptureRecorder.swift
@@ -465,6 +465,12 @@ final class ScreenCaptureRecorder: NSObject, SCStreamOutput, SCStreamDelegate {
 			configuration.setValue(true, forKey: "captureMicrophone")
 			if let deviceId = resolveMicrophoneCaptureDeviceID() {
 				configuration.setValue(deviceId, forKey: "microphoneCaptureDeviceID")
+			} else {
+				emit([
+					"event": "warning",
+					"code": "microphone-defaulted",
+					"message": "The requested microphone could not be resolved; capturing the default input.",
+				])
 			}
 		} else {
 			nativeMicrophoneEnabled = false
diff --git a/src/hooks/useScreenRecorder.nativeMacStartWarning.test.tsx b/src/hooks/useScreenRecorder.nativeMacStartWarning.test.tsx
new file mode 100644
index 000000000..040eeee6a
--- /dev/null
+++ b/src/hooks/useScreenRecorder.nativeMacStartWarning.test.tsx
@@ -0,0 +1,120 @@
+// @vitest-environment jsdom
+import { act, renderHook } from "@testing-library/react";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+vi.mock("@/contexts/I18nContext", () => ({
+	useScopedT: () => (key: string) => key,
+}));
+
+vi.mock("sonner", () => ({
+	toast: { error: vi.fn(), success: vi.fn(), info: vi.fn(), warning: vi.fn() },
+}));
+
+import { toast } from "sonner";
+import { useScreenRecorder } from "./useScreenRecorder";
+
+type ElectronAPI = Window["electronAPI"];
+
+const SOURCE = { id: "screen:0:0", name: "Screen 1", display_id: "1", thumbnail: "" };
+
+let api: Record<string, ReturnType<typeof vi.fn>>;
+
+function stubElectronAPI() {
+	api = {
+		getRecordingPrefs: vi.fn(async () => ({
+			micEnabled: true,
+			micDeviceId: "chromium-device-id",
+			micDeviceName: "USB Microphone",
+			camEnabled: false,
+			camDeviceId: null,
+			systemAudioEnabled: false,
+			cursorCaptureMode: "system",
+		})),
+		getPlatform: vi.fn(() => "darwin"),
+		getSelectedSource: vi.fn(async () => SOURCE),
+		isNativeMacCaptureAvailable: vi.fn(async () => ({ success: true, available: true })),
+		startNativeMacRecording: vi.fn(async () => ({
+			success: true,
+			recordingId: 7,
+			microphoneDefaulted: true,
+		})),
+		stopNativeMacRecording: vi.fn(async () => ({ success: true, discarded: true })),
+		showCountdownOverlay: vi.fn(async () => true),
+		setCountdownOverlayValue: vi.fn(async () => true),
+		hideCountdownOverlay: vi.fn(async () => true),
+	};
+	window.electronAPI = api as unknown as ElectronAPI;
+}
+
+async function settle(ms = 0) {
+	await act(async () => {
+		await vi.advanceTimersByTimeAsync(ms);
+	});
+}
+
+beforeEach(() => {
+	vi.useFakeTimers();
+	stubElectronAPI();
+	vi.mocked(toast.error).mockClear();
+});
+
+afterEach(() => {
+	vi.useRealTimers();
+	vi.restoreAllMocks();
+});
+
+describe("useScreenRecorder native macOS start warnings", () => {
+	it("warns but keeps recording when the selected microphone defaults", async () => {
+		const view = renderHook(() => useScreenRecorder());
+		await settle();
+
+		await act(async () => {
+			view.result.current.toggleRecording();
+		});
+		await settle(3_500);
+
+		expect(api.startNativeMacRecording).toHaveBeenCalledWith(
+			expect.objectContaining({
+				audio: {
+					system: { enabled: false },
+					microphone: expect.objectContaining({
+						enabled: true,
+						deviceId: "chromium-device-id",
+						deviceName: "USB Microphone",
+					}),
+				},
+			}),
+		);
+		expect(view.result.current.recording).toBe(true);
+		expect(toast.error).toHaveBeenCalledWith("recording.microphoneDefaulted");
+	});
+
+	it("does not warn after the recording start is cancelled", async () => {
+		let resolveStart:
+			| ((result: Awaited<ReturnType<ElectronAPI["startNativeMacRecording"]>>) => void)
+			| null = null;
+		api.startNativeMacRecording.mockImplementation(
+			() =>
+				new Promise((resolve) => {
+					resolveStart = resolve;
+				}),
+		);
+		const view = renderHook(() => useScreenRecorder());
+		await settle();
+
+		await act(async () => {
+			view.result.current.toggleRecording();
+		});
+		await settle(3_500);
+		expect(api.startNativeMacRecording).toHaveBeenCalledOnce();
+
+		view.unmount();
+		await act(async () => {
+			resolveStart?.({ success: true, recordingId: 8, microphoneDefaulted: true });
+			await Promise.resolve();
+		});
+
+		expect(api.stopNativeMacRecording).toHaveBeenCalledWith(true);
+		expect(toast.error).not.toHaveBeenCalled();
+	});
+});
diff --git a/src/hooks/useScreenRecorder.ts b/src/hooks/useScreenRecorder.ts
index 14eec5ab4..7507fa153 100644
--- a/src/hooks/useScreenRecorder.ts
+++ b/src/hooks/useScreenRecorder.ts
@@ -1331,6 +1331,9 @@ export function useScreenRecorder(): UseScreenRecorderReturn {
 				await window.electronAPI.stopNativeMacRecording(true);
 				return true;
 			}
+			if (result.microphoneDefaulted) {
+				toast.error(t("recording.microphoneDefaulted"));
+			}
 
 			// The IPC call above only resolves once the helper's stdout confirms its
 			// screen capture has truly started (see waitForNativeMacCaptureStart in
diff --git a/src/lib/nativeMacRecording.ts b/src/lib/nativeMacRecording.ts
index e5137c3de..8364310be 100644
--- a/src/lib/nativeMacRecording.ts
+++ b/src/lib/nativeMacRecording.ts
@@ -88,6 +88,8 @@ export type NativeMacRecordingStartResult = {
 	recordingId?: number;
 	path?: string;
 	helperPath?: string;
+	/** The helper could not resolve the selected device and is using the system default. */
+	microphoneDefaulted?: boolean;
 	error?: string;
 };