diff --git a/src/components/Shell.test.tsx b/src/components/Shell.test.tsx
index d4d34ba..47ad165 100644
--- a/src/components/Shell.test.tsx
+++ b/src/components/Shell.test.tsx
@@ -44,4 +44,5 @@ test('shows nav, endpoint pill, and outlet content when connected', async () =>
   expect(screen.getByText('home content')).toBeInTheDocument()
   await waitFor(() => expect(screen.getByText('127.0.0.1:8731')).toBeInTheDocument())
   expect(screen.queryByText(/connect to your knowledge base/i)).not.toBeInTheDocument()
+  expect(screen.getByRole('button', { name: /toggle theme/i })).toBeInTheDocument()
 })
diff --git a/src/components/Shell.tsx b/src/components/Shell.tsx
index 205c6c0..cfd5817 100644
--- a/src/components/Shell.tsx
+++ b/src/components/Shell.tsx
@@ -118,6 +118,7 @@ export function Shell() {
             <button
               onClick={() => setTheme(theme === 'dark' ? 'light' : 'dark')}
               title="Toggle theme"
+              aria-label="Toggle theme"
               className="rounded-lg p-2 text-sepia transition hover:bg-paper-3 hover:text-ink"
             >
               <SunMoon size={16} />