diff --git a/django/apps/registry.py b/django/apps/registry.py
index c64106cd6f..e75bb99cfe 100644
--- a/django/apps/registry.py
+++ b/django/apps/registry.py
@@ -227,9 +227,7 @@ class Apps(object):
         Returns the app config for the inner application in case of nesting.
         Returns None if the object isn't in any registered app config.
         """
-        # In Django 1.7 and 1.8, it's allowed to call this method at import
-        # time, even while the registry is being populated. In Django 1.9 and
-        # later, that should be forbidden with `self.check_apps_ready()`.
+        self.check_apps_ready()
         candidates = []
         for app_config in self.app_configs.values():
             if object_name.startswith(app_config.name):
diff --git a/tests/apps/tests.py b/tests/apps/tests.py
index 5e23ddb9d1..80cc088f42 100644
--- a/tests/apps/tests.py
+++ b/tests/apps/tests.py
@@ -8,7 +8,7 @@ from unittest import skipUnless
 from django.apps import AppConfig, apps
 from django.apps.registry import Apps
 from django.contrib.admin.models import LogEntry
-from django.core.exceptions import ImproperlyConfigured
+from django.core.exceptions import AppRegistryNotReady, ImproperlyConfigured
 from django.db import models
 from django.test import TestCase, override_settings
 from django.test.utils import extend_sys_path
@@ -247,6 +247,18 @@ class AppsTests(TestCase):
                 "Conflicting 'southponies' models in application 'apps':.*"):
             type(str("SouthPonies"), (models.Model,), body)
 
+    def test_get_containing_app_config_apps_not_ready(self):
+        """
+        apps.get_containing_app_config() should raise an exception if
+        apps.apps_ready isn't True.
+        """
+        apps.apps_ready = False
+        try:
+            with self.assertRaisesMessage(AppRegistryNotReady, "Apps aren't loaded yet"):
+                apps.get_containing_app_config('foo')
+        finally:
+            apps.apps_ready = True
+
 
 class Stub(object):
     def __init__(self, **kwargs):