diff --git a/README.rst b/README.rst
index ec1fa56..455d829 100644
--- a/README.rst
+++ b/README.rst
@@ -107,3 +107,30 @@ Configuration
             {'model': 'auth.User', 'label': 'Staff'},
         )},
     )
+
+4. If you override the default admin site object (django.contrib.admin.site),
+   add the setting `ADMIN_REORDER_SITE` to your settings.py:
+
+   .. code-block:: python
+   
+    # my_project/admin.py
+    from django.contrib import admin
+
+
+    class CustomAdminSite(admin.AdminSite):
+        pass
+
+    custom_admin = CustomAdminSite(name='CustomAdmin')
+
+    # my_project/urls.py
+    from my_project.admin import custom_admin
+
+    urlpatterns = [
+        # ...
+        path('/admin', custom_admin.urls), 
+        # ...
+    ]
+
+
+    # my_project/settings.py
+    ADMIN_REORDER_SITE = 'my_project.admin.custom_admin'
diff --git a/admin_reorder/middleware.py b/admin_reorder/middleware.py
index 9bf0a77..eca2091 100644
--- a/admin_reorder/middleware.py
+++ b/admin_reorder/middleware.py
@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 
 from __future__ import unicode_literals
-
+import importlib
 from copy import deepcopy
 
 from django.conf import settings
@@ -23,6 +23,23 @@
     MiddlewareMixin = object
 
 
+def get_admin_index(request):
+    """Return the admin index from ADMIN_REORDER_SITE setting. If setting is
+    not found, return the index of django.contrib.admin.site.
+    """
+    admin_site = getattr(settings, 'ADMIN_REORDER_SITE', None)
+
+    if admin_site is not None:
+        *admin_module, admin_site = admin_site.split(".")
+
+        admin_module = importlib.import_module('.'.join(admin_module))
+        admin_site = getattr(admin_module, admin_site)
+
+        return admin_site.index(request)
+
+    return admin.site.index(request)
+
+
 class ModelAdminReorder(MiddlewareMixin):
 
     def init_config(self, request, app_list):
@@ -39,7 +56,7 @@ def init_config(self, request, app_list):
                 'ADMIN_REORDER config parameter must be tuple or list. '
                 'Got {config}'.format(config=self.config))
 
-        admin_index = admin.site.index(request)
+        admin_index = get_admin_index(request)
         try:
             # try to get all installed models
             app_list = admin_index.context_data['app_list']
diff --git a/runtests.py b/runtests.py
index 396efbe..5bd8f29 100644
--- a/runtests.py
+++ b/runtests.py
@@ -14,6 +14,7 @@
         ROOT_URLCONF="admin_reorder.urls",
         INSTALLED_APPS=[
             "django.contrib.auth",
+            "django.contrib.admin",
             "django.contrib.contenttypes",
             "django.contrib.sites",
             "admin_reorder",
@@ -32,7 +33,8 @@
 
     from django_nose import NoseTestSuiteRunner
 except ImportError:
-    raise ImportError("To fix this error, run: pip install -r requirements-test.txt")
+    raise ImportError(
+        "To fix this error, run: pip install -r requirements-test.txt")
 
 
 def run_tests(*test_args):
diff --git a/tests/test_get_admin_index_custom_admin_site.py b/tests/test_get_admin_index_custom_admin_site.py
new file mode 100644
index 0000000..6c155c2
--- /dev/null
+++ b/tests/test_get_admin_index_custom_admin_site.py
@@ -0,0 +1,50 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+test_django-modeladmin-reorder
+------------
+
+Tests for `django-modeladmin-reorder` get_admin_index function from middleware
+module.
+"""
+
+from django.contrib import admin
+from django.contrib.auth.admin import UserAdmin, GroupAdmin
+from django.contrib.auth.models import User, Group
+from django.test import RequestFactory, TestCase
+from django.test.utils import override_settings
+from django.urls import path
+
+from admin_reorder import middleware
+import admin_reorder
+
+
+class CustomAdminSite(admin.AdminSite):
+    pass
+
+
+custom_admin = CustomAdminSite(name='CustomAdmin')
+custom_admin.register(User, UserAdmin)
+custom_admin.register(Group, GroupAdmin)
+admin_reorder.custom_admin = custom_admin
+urlpatterns = [path('', custom_admin.urls), ]
+
+
+@override_settings(
+    ROOT_URLCONF=__name__,
+    ADMIN_REORDER_SITE='admin_reorder.custom_admin')
+class Testadmin_reorder(TestCase):
+    def setUp(self):
+        self.factory = RequestFactory()
+        self.user = User.objects.create_superuser(
+            'admin', 'foo@foo.com', 'admin')
+
+    def test_get_admin_index_for_default_admin_site(self):
+        request = self.factory.get('/')
+        request.user = self.user
+        admin_index = middleware.get_admin_index(request)
+        self.assertEqual(
+            custom_admin.index(request).context_data,
+            admin_index.context_data
+        )
diff --git a/tests/test_get_admin_index_default_admin_site.py b/tests/test_get_admin_index_default_admin_site.py
new file mode 100644
index 0000000..1dc9c5d
--- /dev/null
+++ b/tests/test_get_admin_index_default_admin_site.py
@@ -0,0 +1,38 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+test_django-modeladmin-reorder
+------------
+
+Tests for `django-modeladmin-reorder` get_admin_index function from middleware
+module.
+"""
+
+from django.contrib import admin
+from django.contrib.auth.models import User
+from django.test import RequestFactory, TestCase
+from django.test.utils import override_settings
+from django.urls import path
+
+from admin_reorder import middleware
+
+
+urlpatterns = [path('', admin.site.urls), ]
+
+
+@override_settings(ROOT_URLCONF=__name__)
+class Testadmin_reorder(TestCase):
+    def setUp(self):
+        self.factory = RequestFactory()
+        self.user = User.objects.create_superuser(
+            'admin', 'foo@foo.com', 'admin')
+
+    def test_get_admin_index_for_default_admin_site(self):
+        request = self.factory.get('/')
+        request.user = self.user
+        admin_index = middleware.get_admin_index(request)
+        self.assertEqual(
+            admin.site.index(request).context_data,
+            admin_index.context_data
+        )