diff --git a/django/apps/registry.py b/django/apps/registry.py
index 0602c4ff57..269787545d 100644
--- a/django/apps/registry.py
+++ b/django/apps/registry.py
@@ -208,7 +208,7 @@ class Apps(object):
                 warnings.warn(
                     "Model '%s.%s' was already registered. "
                     "Reloading models is not advised as it can lead to inconsistencies, "
-                    "most notably with related models." % (model_name, app_label),
+                    "most notably with related models." % (app_label, model_name),
                     RuntimeWarning, stacklevel=2)
             else:
                 raise RuntimeError(
diff --git a/tests/apps/tests.py b/tests/apps/tests.py
index c199fa156d..3dfd88f136 100644
--- a/tests/apps/tests.py
+++ b/tests/apps/tests.py
@@ -237,7 +237,7 @@ class AppsTests(SimpleTestCase):
             self.assertEqual(len(w), 1)
             self.assertTrue(issubclass(w[-1].category, RuntimeWarning))
             self.assertEqual(str(w[-1].message),
-                 "Model 'southponies.apps' was already registered. "
+                 "Model 'apps.southponies' was already registered. "
                  "Reloading models is not advised as it can lead to inconsistencies, "
                  "most notably with related models.")