diff --git a/django/test/client.py b/django/test/client.py
index bbd8239c33..b02d298418 100644
--- a/django/test/client.py
+++ b/django/test/client.py
@@ -262,7 +262,7 @@ class Client:
             self.cookies[settings.SESSION_COOKIE_NAME]['expires'] = None
 
             # Save the session values
-            request.session.save()   
+            request.session.save()
 
             return True
         else:
@@ -274,5 +274,5 @@ class Client:
         Causes the authenticated user to be logged out.
         """
         session = __import__(settings.SESSION_ENGINE, {}, {}, ['']).SessionStore()
-        session.delete(session_key=self.cookies['sessionid'].value)
+        session.delete(session_key=self.cookies[settings.SESSION_COOKIE_NAME].value)
         self.cookies = SimpleCookie()