diff --git a/setup.py b/setup.py
index 8d8721351..1763c7764 100755
--- a/setup.py
+++ b/setup.py
@@ -44,7 +44,7 @@ def get_packages(package):
 env_marker_below_38 = "python_version < '3.8'"
 
 minimal_requirements = [
-    "asgiref>=3.3.4",
+    "asgiref>=3.4.0",
     "click>=7.*",
     "h11>=0.8",
     "typing-extensions;" + env_marker_below_38,
diff --git a/uvicorn/middleware/proxy_headers.py b/uvicorn/middleware/proxy_headers.py
index 5d11436c6..5445e7b4d 100644
--- a/uvicorn/middleware/proxy_headers.py
+++ b/uvicorn/middleware/proxy_headers.py
@@ -16,7 +16,7 @@
     ASGISendCallable,
     HTTPScope,
     Scope,
-    WebsocketScope,
+    WebSocketScope,
 )
 
 
@@ -47,7 +47,7 @@ async def __call__(
         self, scope: Scope, receive: ASGIReceiveCallable, send: ASGISendCallable
     ) -> None:
         if scope["type"] in ("http", "websocket"):
-            scope = cast(Union[HTTPScope, WebsocketScope], scope)
+            scope = cast(Union[HTTPScope, WebSocketScope], scope)
             client_addr: Optional[Tuple[str, int]] = scope.get("client")
             client_host = client_addr[0] if client_addr else None