diff --git a/src/turbosloth/__main__.py b/src/turbosloth/__main__.py
index 07b8021..30a4f70 100644
--- a/src/turbosloth/__main__.py
+++ b/src/turbosloth/__main__.py
@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 from turbosloth import SlothApp
+from turbosloth.exceptions import NotFoundException
 from turbosloth.types import Scope, Receive, Send
 
 app = SlothApp()
diff --git a/src/turbosloth/app.py b/src/turbosloth/app.py
index 7a9d9cb..a47ae75 100644
--- a/src/turbosloth/app.py
+++ b/src/turbosloth/app.py
@@ -1,5 +1,6 @@
 from typing import Optional, Callable, Awaitable, Protocol
 
+from .exceptions import HTTPException
 from .router import Router
 from .types import Scope, Receive, Send, MethodType, HandlerType
 
@@ -18,21 +19,19 @@ class HTTPApp(ASGIApp):
 
         try:
             handler = self.router.match(method, path)
-        except KeyError:
-            # 404
+            await handler(scope, receive, send)
+        except HTTPException as e:
             await send({
                 'type': 'http.response.start',
-                'status': 404,
+                'status': e.code,
                 'headers': [(b'content-type', b'text/plain')],
             })
             await send({
                 'type': 'http.response.body',
-                'body': b'Not Found',
+                'body': str(e).encode(),
             })
             return
 
-        await handler(scope, receive, send)
-
 
 class WSApp(ASGIApp):
     async def _do_websocket(self, scope: Scope, receive: Receive, send: Send):