diff --git a/starlette/authentication.py b/starlette/authentication.py
index 95a65473..5a768368 100644
--- a/starlette/authentication.py
+++ b/starlette/authentication.py
@@ -4,7 +4,7 @@ import inspect
 import typing
 
 from starlette.exceptions import HTTPException
-from starlette.requests import Request
+from starlette.requests import Request, HTTPConnection
 from starlette.responses import RedirectResponse, Response
 
 
@@ -68,7 +68,7 @@ class AuthenticationError(Exception):
 
 class AuthenticationBackend:
     async def authenticate(
-        self, request: Request
+        self, conn: HTTPConnection
     ) -> typing.Optional[typing.Tuple["AuthCredentials", "BaseUser"]]:
         raise NotImplemented()  # pragma: no cover
 
diff --git a/starlette/middleware/authentication.py b/starlette/middleware/authentication.py
index 62b09ec6..6f8d95cd 100644
--- a/starlette/middleware/authentication.py
+++ b/starlette/middleware/authentication.py
@@ -7,7 +7,7 @@ from starlette.authentication import (
     AuthenticationError,
     UnauthenticatedUser,
 )
-from starlette.requests import Request
+from starlette.requests import HTTPConnection
 from starlette.responses import PlainTextResponse, Response
 from starlette.types import ASGIApp, ASGIInstance, Receive, Scope, Send
 
@@ -17,25 +17,27 @@ class AuthenticationMiddleware:
         self,
         app: ASGIApp,
         backend: AuthenticationBackend,
-        on_error: typing.Callable[[Request, AuthenticationError], Response] = None,
+        on_error: typing.Callable[
+            [HTTPConnection, AuthenticationError], Response
+        ] = None,
     ) -> None:
         self.app = app
         self.backend = backend
         self.on_error = (
             on_error if on_error is not None else self.default_on_error
-        )  # type: typing.Callable[[Request, AuthenticationError], Response]
+        )  # type: typing.Callable[[HTTPConnection, AuthenticationError], Response]
 
     def __call__(self, scope: Scope) -> ASGIInstance:
-        if scope["type"] in ["http", "websockets"]:
+        if scope["type"] in ["http", "websocket"]:
             return functools.partial(self.asgi, scope=scope)
         return self.app(scope)
 
     async def asgi(self, receive: Receive, send: Send, scope: Scope) -> None:
-        request = Request(scope, receive=receive)
+        conn = HTTPConnection(scope, receive=receive)
         try:
-            auth_result = await self.backend.authenticate(request)
+            auth_result = await self.backend.authenticate(conn)
         except AuthenticationError as exc:
-            response = self.on_error(request, exc)
+            response = self.on_error(conn, exc)
             await response(receive, send)
             return
 
@@ -46,5 +48,5 @@ class AuthenticationMiddleware:
         await inner(receive, send)
 
     @staticmethod
-    def default_on_error(request: Request, exc: Exception) -> Response:
+    def default_on_error(conn: HTTPConnection, exc: Exception) -> Response:
         return PlainTextResponse(str(exc), status_code=400)