diff --git a/actstream/registry.py b/actstream/registry.py
index f44dd385..8844df0f 100644
--- a/actstream/registry.py
+++ b/actstream/registry.py
@@ -59,7 +59,7 @@ def is_installed(model_class):
     """
     Returns True if a model_class is installed.
     """
-    return model_class._meta.installed
+    return model_class._meta.app_config is not None
 
 
 def validate(model_class, exception_class=ImproperlyConfigured):
diff --git a/tox.ini b/tox.ini
index fd7e997d..db60112d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -2,6 +2,7 @@
 envlist =
     py{37,38,39}-django32-{mysql,postgres,sqlite}
     py{38,39}-django40-{mysql,postgres,sqlite}
+    py{38,39}-django41-{mysql,postgres,sqlite}
 toxworkdir=/tmp/.tox
 
 [testenv]
@@ -18,6 +19,7 @@ deps =
     coverage>=4.5.1
     django32: Django>=3.2,<4.0
     django40: Django>=4.0,<4.1
+    django41: Django>=4.1,<4.2
     mysql: mysqlclient>=2.0.0
     mysql: django-mysql>=2.4.1
     postgres: psycopg2-binary>=2.8