From 8a0a360505b1c147be856aac6ec7a68f405e4bce Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Javier=20S=C3=A1nchez=20Castro?=
 <72013291+JavierSanchezCastro@users.noreply.github.com>
Date: Thu, 11 Apr 2024 10:16:50 +0100
Subject: [PATCH] Update routing.py

---
 fastapi/routing.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fastapi/routing.py b/fastapi/routing.py
index fa1351859..8842745bd 100644
--- a/fastapi/routing.py
+++ b/fastapi/routing.py
@@ -1204,6 +1204,7 @@ class APIRouter(routing.Router):
         app.include_router(internal_router)
         ```
         """
+        assert self != router, "Router cannot be the same as parent"
         if prefix:
             assert prefix.startswith("/"), "A path prefix must start with '/'"
             assert not prefix.endswith(