diff --git a/src/turbosloth/app.py b/src/turbosloth/app.py
index 476be8e..f3b99a5 100644
--- a/src/turbosloth/app.py
+++ b/src/turbosloth/app.py
@@ -12,7 +12,7 @@ from .interfaces.serialize_selector import SerializeSelector
 from .interfaces.serialized import SerializedResponse, SerializedRequest
 from .interfaces.serialized.text import TextSerializedResponse
 from .req_schema import UnwrappedRequest
-from .router import Router
+from .router import Router, Route
 from .types import HandlerType, InternalHandlerType, ContentType
 from .internal_types import Scope, Receive, Send, MethodType, QTYPE, BTYPE, PTYPE
 from breakshaft.convertor import ConvRepo
@@ -26,6 +26,9 @@ class ASGIApp(Protocol):
     def route(self, method: MethodType, path_pattern: str):
         raise RuntimeError('stub!')
 
+    def add_subroute(self, subr: Route | Router, basepath: str) -> None:
+        self.router.add_subroute(subr, basepath)
+
 
 class HTTPApp(ASGIApp):
     serialize_selector: SerializeSelector
diff --git a/src/turbosloth/router.py b/src/turbosloth/router.py
index 4cd0922..e5051be 100644
--- a/src/turbosloth/router.py
+++ b/src/turbosloth/router.py
@@ -177,7 +177,7 @@ class Router:
             raise NotFoundException(path or '/')
         return h
 
-    def add_subroute(self, basepath: str, subr: Route | Router):
+    def add_subroute(self, subr: Route | Router, basepath: str):
         if isinstance(subr, Router):
             subr = subr._root
 
diff --git a/tests/test_router.py b/tests/test_router.py
index 9af2bfd..62c6269 100644
--- a/tests/test_router.py
+++ b/tests/test_router.py
@@ -93,18 +93,18 @@ def test_subroutes():
 
     r1.add('GET', '/asdf', f)
     r2.add('GET', '/asdf/a', d)
-    r1.add_subroute('', r2)
+    r1.add_subroute(r2, '')
 
     assert r1.match('GET', '/asdf') == ({}, f)
     assert r1.match('GET', '/asdf/a') == ({}, d)
-    r1.add_subroute('/asdf', r2)
+    r1.add_subroute(r2, '/asdf')
     assert r1.match('GET', '/asdf/asdf/a') == ({}, d)
 
-    r1.add_subroute('/asdf' * 5, r2)
+    r1.add_subroute(r2, '/asdf' * 5)
     assert r1.match('GET', '/asdf' * 5 + '/asdf/a') == ({}, d)
 
     with pytest.raises(NotFoundException):
         r1.match('GET', '/asdf/' * 5 + '/asdf/a')
 
-    r1.add_subroute('/asdf/' * 5, r2)
+    r1.add_subroute(r2, '/asdf/' * 5)
     assert r1.match('GET', '/asdf/' * 5 + '/asdf/a') == ({}, d)