diff --git a/src/app/api/profile/update/route.js b/src/app/api/profile/update/route.js
index c057a163..dbc971bd 100644
--- a/src/app/api/profile/update/route.js
+++ b/src/app/api/profile/update/route.js
@@ -1,6 +1,18 @@
 import { NextResponse } from 'next/server';
 import { createSupabaseServerClient } from '@/lib/supabase.js';
 
+/**
+ * @param {string | null} authHeader
+ * @returns {string | null}
+ */
+function getBearerToken(authHeader) {
+	if (typeof authHeader !== 'string') return null;
+
+	const match = authHeader.match(/^Bearer\s+(.+)$/i);
+	const token = match?.[1]?.trim();
+
+	return token || null;
+}
 
 export async function POST(request, { params } = {}) {
 	try {
@@ -8,13 +20,13 @@ export async function POST(request, { params } = {}) {
 
 		// Get authorization header
 		const authHeader = request.headers.get('authorization');
-		if (!authHeader?.startsWith('Bearer ')) {
+		const token = getBearerToken(authHeader);
+		if (!token) {
 			return NextResponse.json({ error: 'Missing or invalid authorization header' }, { status: 401 });
 		}
 
 		// Create Supabase client and set session
 		const supabase = await createSupabaseServerClient();
-		const token = authHeader.replace('Bearer ', '');
 
 		// Set the session to ensure auth.uid() is available for RLS
 		const { data: { user }, error: authError } = await supabase.auth.getUser(token);
@@ -103,4 +115,4 @@ export async function POST(request, { params } = {}) {
 		console.error('Profile update error:', err);
 		return NextResponse.json({ error: 'Internal server error' }, { status: 500 });
 	}
-}
\ No newline at end of file
+}
diff --git a/src/app/api/profile/update/route.test.js b/src/app/api/profile/update/route.test.js
new file mode 100644
index 00000000..ee04e083
--- /dev/null
+++ b/src/app/api/profile/update/route.test.js
@@ -0,0 +1,79 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+const mocks = vi.hoisted(() => ({
+	getUser: vi.fn(),
+	setSession: vi.fn(),
+	createSupabaseServerClient: vi.fn(() => ({
+		auth: {
+			getUser: mocks.getUser,
+			setSession: mocks.setSession
+		},
+		from: vi.fn(() => ({
+			update: vi.fn(() => ({
+				eq: vi.fn(() => ({
+					select: vi.fn(() => ({
+						data: [{
+							id: 'row-1',
+							username: 'alice',
+							display_name: 'Alice',
+							avatar_url: null,
+							bio: 'hello',
+							website: null
+						}],
+						error: null
+					}))
+				}))
+			}))
+		}))
+	}))
+}));
+
+vi.mock('@/lib/supabase.js', () => ({
+	createSupabaseServerClient: mocks.createSupabaseServerClient
+}));
+
+function profileRequest(authorization) {
+	return new Request('https://example.com/api/profile/update', {
+		method: 'POST',
+		headers: authorization ? { authorization } : {},
+		body: JSON.stringify({ bio: 'hello' })
+	});
+}
+
+describe('profile update bearer authentication', () => {
+	beforeEach(() => {
+		vi.resetModules();
+		vi.clearAllMocks();
+		mocks.getUser.mockResolvedValue({
+			data: { user: { id: 'user-1', email: 'alice@example.com', phone: null } },
+			error: null
+		});
+	});
+
+	it('normalizes bearer scheme casing and extra spaces before validating the token', async () => {
+		const { POST } = await import('./route.js');
+
+		const response = await POST(profileRequest('bearer   access-token-123  '));
+		const body = await response.json();
+
+		expect(response.status).toBe(200);
+		expect(body.success).toBe(true);
+		expect(mocks.getUser).toHaveBeenCalledWith('access-token-123');
+		expect(mocks.setSession).toHaveBeenCalledWith({
+			access_token: 'access-token-123',
+			refresh_token: ''
+		});
+	});
+
+	it('rejects an empty bearer header before creating a Supabase client', async () => {
+		const { POST } = await import('./route.js');
+
+		const response = await POST(profileRequest('Bearer   '));
+		const body = await response.json();
+
+		expect(response.status).toBe(401);
+		expect(body.error).toBe('Missing or invalid authorization header');
+		expect(mocks.createSupabaseServerClient).not.toHaveBeenCalled();
+		expect(mocks.getUser).not.toHaveBeenCalled();
+	});
+});