diff --git a/django/contrib/sessions/backends/db.py b/django/contrib/sessions/backends/db.py
index d1496d63bf..0f79d9ee1a 100644
--- a/django/contrib/sessions/backends/db.py
+++ b/django/contrib/sessions/backends/db.py
@@ -10,40 +10,42 @@ class SessionStore(SessionBase):
     """
     def __init__(self, session_key=None):
         super(SessionStore, self).__init__(session_key)
-    
+
     def load(self):
         try:
             s = Session.objects.get(
-                session_key = self.session_key, 
+                session_key = self.session_key,
                 expire_date__gt=datetime.datetime.now()
             )
             return self.decode(s.session_data)
         except (Session.DoesNotExist, SuspiciousOperation):
-            
+
             # Create a new session_key for extra security.
             self.session_key = self._get_new_session_key()
             self._session_cache = {}
 
             # Save immediately to minimize collision
             self.save()
+            # Ensure the user is notified via a new cookie.
+            self.modified = True
             return {}
-            
+
     def exists(self, session_key):
         try:
             Session.objects.get(session_key=session_key)
         except Session.DoesNotExist:
             return False
         return True
-            
+
     def save(self):
         Session.objects.create(
             session_key = self.session_key,
             session_data = self.encode(self._session),
             expire_date = datetime.datetime.now() + datetime.timedelta(seconds=settings.SESSION_COOKIE_AGE)
         )
-    
+
     def delete(self, session_key):
         try:
             Session.objects.get(session_key=session_key).delete()
         except Session.DoesNotExist:
-            pass
\ No newline at end of file
+            pass
diff --git a/django/contrib/sessions/backends/file.py b/django/contrib/sessions/backends/file.py
index a8c3c69b10..cd3e3d9c75 100644
--- a/django/contrib/sessions/backends/file.py
+++ b/django/contrib/sessions/backends/file.py
@@ -10,31 +10,31 @@ class SessionStore(SessionBase):
     """
     def __init__(self, session_key=None):
         self.storage_path = getattr(settings, "SESSION_FILE_PATH", tempfile.gettempdir())
-        
+
         # Make sure the storage path is valid.
         if not os.path.isdir(self.storage_path):
             raise ImproperlyConfigured("The session storage path %r doesn't exist. "\
                                        "Please set your SESSION_FILE_PATH setting "\
                                        "to an existing directory in which Django "\
                                        "can store session data." % self.storage_path)
-        
-        self.file_prefix = settings.SESSION_COOKIE_NAME    
+
+        self.file_prefix = settings.SESSION_COOKIE_NAME
         super(SessionStore, self).__init__(session_key)
-    
+
     def _key_to_file(self, session_key=None):
         """
         Get the file associated with this session key.
         """
         if session_key is None:
             session_key = self.session_key
-        
+
         # Make sure we're not vulnerable to directory traversal. Session keys
         # should always be md5s, so they should never contain directory components.
         if os.path.sep in session_key:
             raise SuspiciousOperation("Invalid characters (directory components) in session key")
-            
+
         return os.path.join(self.storage_path, self.file_prefix + session_key)
-            
+
     def load(self):
         session_data = {}
         try:
@@ -46,6 +46,8 @@ class SessionStore(SessionBase):
                     self._session_key = self._get_new_session_key()
                     self._session_cache = {}
                     self.save()
+                    # Ensure the user is notified via a new cookie.
+                    self.modified = True
             finally:
                 session_file.close()
         except(IOError):
@@ -66,12 +68,12 @@ class SessionStore(SessionBase):
         if os.path.exists(self._key_to_file(session_key)):
             return True
         return False
-        
+
     def delete(self, session_key):
         try:
             os.unlink(self._key_to_file(session_key))
         except OSError:
             pass
-            
+
     def clean(self):
         pass