diff --git a/packages/tuono-router/src/components/NotFound.spec.tsx b/packages/tuono-router/src/components/NotFound.spec.tsx
new file mode 100644
index 00000000..1f82d23d
--- /dev/null
+++ b/packages/tuono-router/src/components/NotFound.spec.tsx
@@ -0,0 +1,114 @@
+import type { HTMLAttributes, JSX } from 'react'
+import { afterEach, describe, expect, it, vi } from 'vitest'
+
+import { cleanup, render, screen } from '@testing-library/react'
+
+import { Route } from '../route'
+import type { RouteComponent, RouteProps } from '../types'
+
+import { NotFound } from './NotFound'
+
+function createRouteComponent(
+  routeType: string,
+  RouteComponentFn: (props: RouteProps) => JSX.Element,
+): RouteComponent {
+  const RootComponent = RouteComponentFn as RouteComponent
+  RootComponent.preload = vi.fn()
+  RootComponent.displayName = routeType
+  return RootComponent
+}
+
+const root = new Route({
+  isRoot: true,
+  component: createRouteComponent('root', ({ children }) => (
+    <div data-testid="root">{children}</div>
+  )),
+})
+
+vi.mock('./Link', () => ({
+  Link: (props: HTMLAttributes<HTMLAnchorElement>): JSX.Element => (
+    <a {...props} />
+  ),
+}))
+
+vi.mock('../hooks/useServerPayloadData.ts', () => ({
+  useServerPayloadData: (): { data: unknown; isLoading: boolean } => {
+    return {
+      data: undefined,
+      isLoading: false,
+    }
+  },
+}))
+
+const { useRouterContext } = vi.hoisted(() => {
+  return { useRouterContext: vi.fn() }
+})
+
+vi.mock('../components/RouterContext', () => ({
+  useRouterContext,
+}))
+
+describe('<NotFound />', () => {
+  afterEach(cleanup)
+
+  describe('when a custom 404 page exists', () => {
+    it('should render the custom 404 page', () => {
+      useRouterContext.mockReturnValue({
+        router: {
+          routesById: {
+            '/404': new Route({
+              getParentRoute: (): Route => root,
+              component: createRouteComponent('404', () => (
+                <div data-testid="404">custom 404</div>
+              )),
+            }),
+            __root__: root,
+          },
+        },
+      })
+      render(<NotFound />)
+      expect(screen.getByTestId('root')).toMatchInlineSnapshot(
+        `
+        <div
+          data-testid="root"
+        >
+          <div
+            data-testid="404"
+          >
+            custom 404
+          </div>
+        </div>
+        `,
+      )
+    })
+  })
+
+  describe('when a custom 404 page does not exist', () => {
+    it('should render the default 404 page, wrapped by the root __layout', () => {
+      useRouterContext.mockReturnValue({
+        router: {
+          routesById: {
+            __root__: root,
+          },
+        },
+      })
+      render(<NotFound />)
+      expect(screen.getByTestId('root')).toMatchInlineSnapshot(
+        `
+        <div
+          data-testid="root"
+        >
+          <h1>
+            404 Not found
+          </h1>
+          <a
+            href="/"
+          >
+            Return home
+          </a>
+        </div>
+        `,
+      )
+    })
+  })
+})
diff --git a/packages/tuono-router/src/components/NotFound.tsx b/packages/tuono-router/src/components/NotFound.tsx
index 2c3a68fa..7ad4e186 100644
--- a/packages/tuono-router/src/components/NotFound.tsx
+++ b/packages/tuono-router/src/components/NotFound.tsx
@@ -1,11 +1,12 @@
 import type { JSX } from 'react'
 
 import { useRouterContext } from '../components/RouterContext'
+import { ROOT_ROUTE_ID } from '../route'
 
 import { RouteMatch } from './RouteMatch'
 import { Link } from './Link'
 
-export function NotFound(): JSX.Element {
+export function NotFound(): JSX.Element | null {
   const { router } = useRouterContext()
 
   const custom404Route = router.routesById['/404']
@@ -15,10 +16,14 @@ export function NotFound(): JSX.Element {
     return <RouteMatch route={custom404Route} serverInitialData={{}} />
   }
 
+  const RootLayout = router.routesById[ROOT_ROUTE_ID]?.component
+
+  if (!RootLayout) return null
+
   return (
-    <>
+    <RootLayout data={null} isLoading={false}>
       <h1>404 Not found</h1>
       <Link href="/">Return home</Link>
-    </>
+    </RootLayout>
   )
 }
diff --git a/packages/tuono-router/src/route.ts b/packages/tuono-router/src/route.ts
index 33bc7c28..a751c86b 100644
--- a/packages/tuono-router/src/route.ts
+++ b/packages/tuono-router/src/route.ts
@@ -14,7 +14,7 @@ export function createRoute(options: RouteOptions): Route {
   return new Route(options)
 }
 
-const rootRouteId = '__root__'
+export const ROOT_ROUTE_ID = '__root__'
 
 export class Route {
   options: RouteOptions
@@ -47,10 +47,10 @@ export class Route {
     this.parentRoute = this.options.getParentRoute?.()
 
     if (isRoot) {
-      this.path = rootRouteId
+      this.path = ROOT_ROUTE_ID
     }
 
-    let path: undefined | string = isRoot ? rootRouteId : this.options.path
+    let path: undefined | string = isRoot ? ROOT_ROUTE_ID : this.options.path
 
     // If the path is anything other than an index path, trim it up
     if (path && path !== '/') {
@@ -60,17 +60,17 @@ export class Route {
     const customId = this.options.id || path
 
     // Strip the parentId prefix from the first level of children
-    let id = isRoot ? rootRouteId : joinPaths([customId])
+    let id = isRoot ? ROOT_ROUTE_ID : joinPaths([customId])
 
-    if (path === rootRouteId) {
+    if (path === ROOT_ROUTE_ID) {
       path = '/'
     }
 
-    if (id !== rootRouteId) {
+    if (id !== ROOT_ROUTE_ID) {
       id = joinPaths(['/', id])
     }
 
-    const fullPath = id === rootRouteId ? '/' : path
+    const fullPath = id === ROOT_ROUTE_ID ? '/' : path
 
     this.path = path
     this.id = id