diff --git a/django/contrib/auth/middleware.py b/django/contrib/auth/middleware.py
index 3afd1083c7..ae7d868134 100644
--- a/django/contrib/auth/middleware.py
+++ b/django/contrib/auth/middleware.py
@@ -1,22 +1,20 @@
 class LazyUser(object):
-    def __init__(self, session):
-        self.session = session
+    def __init__(self):
         self._user = None
 
     def __get__(self, request, obj_type=None):
         if self._user is None:
             from django.contrib.auth.models import User, AnonymousUser, SESSION_KEY
             try:
-                user_id = self.session[SESSION_KEY]
+                user_id = request.session[SESSION_KEY]
                 self._user = User.objects.get(pk=user_id)
             except (KeyError, User.DoesNotExist):
                 self._user = AnonymousUser()
-            del self.session # We don't need to keep this around anymore.
         return self._user
 
 class AuthenticationMiddleware:
     def process_request(self, request):
         from django.contrib.auth.models import SESSION_KEY
         assert hasattr(request, 'session'), "The Django authentication middleware requires session middleware to be installed. Edit your MIDDLEWARE_CLASSES setting to insert 'django.contrib.sessions.middleware.SessionMiddleware'."
-        request.__class__.user = LazyUser(request.session)
+        request.__class__.user = LazyUser()
         return None