diff --git a/tests/test_web_functional.py b/tests/test_web_functional.py
index 30976d7377a..89535ec9899 100644
--- a/tests/test_web_functional.py
+++ b/tests/test_web_functional.py
@@ -196,6 +196,29 @@ async def handler(request: web.Request) -> web.Response:
     resp.release()
 
 
+async def test_content_length_invalid(
+    aiohttp_client: AiohttpClient,
+) -> None:
+    async def handler(request: web.Request) -> web.Response:
+        body = await request.read()
+        return web.Response(body=body)
+
+    app = web.Application()
+    app.router.add_post("/", handler)
+    client = await aiohttp_client(app)
+
+    resp = await client.post("/", data=b"hello world", headers={CONTENT_LENGTH: "11"})
+    assert resp.status == 200
+    assert await resp.read() == b"hello world"
+    resp.release()
+
+    with pytest.raises(ValueError, match="Invalid Content-Length header"):
+        await client.post("/", data=b"hello world", headers={CONTENT_LENGTH: "-100"})
+
+    with pytest.raises(ValueError, match="Invalid Content-Length header"):
+        await client.post("/", data=b"hello world", headers={CONTENT_LENGTH: " 100"})
+
+
 @pytest.mark.skipif(sys.version_info < (3, 11), reason="Needs Task.cancelling()")
 async def test_cancel_shutdown(aiohttp_client: AiohttpClient) -> None:
     async def handler(request: web.Request) -> web.Response: