diff --git a/aiogram/dispatcher/router.py b/aiogram/dispatcher/router.py
index 812bf45b..72e69119 100644
--- a/aiogram/dispatcher/router.py
+++ b/aiogram/dispatcher/router.py
@@ -262,7 +262,7 @@ class Router:
         :return:
         """
         if not isinstance(router, Router):
-            msg = f"router should be instance of Router not {type(router).__class__.__name__}"
+            msg = f"router should be instance of Router not {type(router).__name__!r}"
             raise ValueError(msg)
         router.parent_router = self
         return router
diff --git a/tests/test_dispatcher/test_router.py b/tests/test_dispatcher/test_router.py
index 1ac78480..e7884b1c 100644
--- a/tests/test_dispatcher/test_router.py
+++ b/tests/test_dispatcher/test_router.py
@@ -50,7 +50,9 @@ class TestRouter:
 
     def test_include_router_by_string_bad_type(self):
         router = Router()
-        with pytest.raises(ValueError, match=r"router should be instance of Router"):
+        with pytest.raises(
+            ValueError, match=r"router should be instance of Router not 'TestRouter'"
+        ):
             router.include_router(self)
 
     def test_set_parent_router_bad_type(self):