diff --git a/slowapi/extension.py b/slowapi/extension.py
index 050f882..f7d85f4 100644
--- a/slowapi/extension.py
+++ b/slowapi/extension.py
@@ -326,13 +326,6 @@ def emit(*_):
             self._fallback_storage = MemoryStorage()
             self._fallback_limiter = STRATEGIES[strategy](self._fallback_storage)
 
-    def slowapi_startup(self) -> None:
-        """
-        Starlette startup event handler that links the app with the Limiter instance.
-        """
-        app.state.limiter = self  # type: ignore
-        app.add_exception_handler(RateLimitExceeded, _rate_limit_exceeded_handler)  # type: ignore
-
     def get_app_config(self, key: str, default_value: T = None) -> T:
         """
         Place holder until we find a better way to load config from app
@@ -486,7 +479,7 @@ def __evaluate_limits(
         failed_limit = None
         limit_for_header = None
         for lim in limits:
-            limit_scope = lim.scope or endpoint
+            limit_scope = lim.scope_for(request) or endpoint
             if lim.is_exempt(request):
                 continue
             if lim.methods is not None and request.method.lower() not in lim.methods:
diff --git a/slowapi/wrappers.py b/slowapi/wrappers.py
index d5677d4..94cf790 100644
--- a/slowapi/wrappers.py
+++ b/slowapi/wrappers.py
@@ -51,18 +51,12 @@ def is_exempt(self, request: Optional[Request] = None) -> bool:
             return self.exempt_when(request)
         return self.exempt_when()
 
-    @property
-    def scope(self) -> str:
-        # flack.request.endpoint is the name of the function for the endpoint
-        # FIXME: how to get the request here?
+    def scope_for(self, request: Request) -> str:
         if self.__scope is None:
             return ""
-        else:
-            return (
-                self.__scope(request.endpoint)  # type: ignore
-                if callable(self.__scope)
-                else self.__scope
-            )
+        if callable(self.__scope):
+            return self.__scope(request)
+        return self.__scope
 
 
 class LimitGroup(object):
diff --git a/tests/test_starlette_extension.py b/tests/test_starlette_extension.py
index 0e26baa..6c0414b 100644
--- a/tests/test_starlette_extension.py
+++ b/tests/test_starlette_extension.py
@@ -121,6 +121,36 @@ def t2(request: Request):
         # the shared limit has already been hit via t1
         assert client.get("/t2").status_code == 429
 
+    def test_shared_decorator_callable_scope(self, build_starlette_app):
+        """Callable scope receives the request and buckets are keyed by its return value."""
+        app, limiter = build_starlette_app(key_func=get_ipaddr)
+
+        def scope_from_tenant(request: Request) -> str:
+            return request.headers.get("X-Tenant", "default")
+
+        shared_lim = limiter.shared_limit("5/minute", scope=scope_from_tenant)
+
+        @shared_lim
+        def t1(request: Request):
+            return PlainTextResponse("test")
+
+        @shared_lim
+        def t2(request: Request):
+            return PlainTextResponse("test")
+
+        app.add_route("/t1", t1)
+        app.add_route("/t2", t2)
+
+        client = TestClient(app)
+        # tenant A burns its budget on /t1 ...
+        for i in range(10):
+            resp = client.get("/t1", headers={"X-Tenant": "A"})
+            assert resp.status_code == (200 if i < 5 else 429)
+        # ... and /t2 is also exhausted for tenant A (shared scope)
+        assert client.get("/t2", headers={"X-Tenant": "A"}).status_code == 429
+        # but tenant B has its own bucket — scope callable isolates them
+        assert client.get("/t2", headers={"X-Tenant": "B"}).status_code == 200
+
     def test_multiple_decorators(self, build_starlette_app):
         app, limiter = build_starlette_app(key_func=get_ipaddr)