diff --git a/tests/runtests.py b/tests/runtests.py
index 843850074b..2d3b737cec 100755
--- a/tests/runtests.py
+++ b/tests/runtests.py
@@ -107,8 +107,7 @@ def django_tests(verbosity, interactive, test_labels):
         'django.contrib.auth.middleware.AuthenticationMiddleware',
         'django.middleware.common.CommonMiddleware',
     )
-    if not hasattr(settings, 'SITE_ID'):
-        settings.SITE_ID = 1
+    settings.SITE_ID = 1
 
     # Load all the ALWAYS_INSTALLED_APPS.
     # (This import statement is intentionally delayed until after we