diff --git a/awx/main/signals.py b/awx/main/signals.py
index 52bd5e55c0..5021f53290 100644
--- a/awx/main/signals.py
+++ b/awx/main/signals.py
@@ -400,6 +400,12 @@ model_serializer_mapping = {
     AdHocCommand: AdHocCommandSerializer,
     NotificationTemplate: NotificationTemplateSerializer,
     Notification: NotificationSerializer,
+    CredentialType: CredentialTypeSerializer,
+    Schedule: ScheduleSerializer,
+    Label: LabelSerializer,
+    WorkflowJobTemplate: WorkflowJobTemplateSerializer,
+    WorkflowJobTemplateNode: WorkflowJobTemplateNodeSerializer,
+    WorkflowJob: WorkflowJobSerializer,
 }
 
 
diff --git a/awx/main/tests/functional/models/test_activity_stream.py b/awx/main/tests/functional/models/test_activity_stream.py
index 7253999fb7..f13ce48f20 100644
--- a/awx/main/tests/functional/models/test_activity_stream.py
+++ b/awx/main/tests/functional/models/test_activity_stream.py
@@ -16,6 +16,7 @@ from awx.main.models import (
 
 # other AWX
 from awx.main.utils import model_to_dict
+from awx.main.utils.common import get_allowed_fields
 from awx.api.serializers import InventorySourceSerializer
 
 # Django
@@ -181,3 +182,20 @@ def test_annon_user_action():
         inv = Inventory.objects.create(name='ainventory')
     entry = inv.activitystream_set.filter(operation='create').first()
     assert not entry.actor
+
+
+@pytest.mark.django_db
+def test_modified_not_allowed_field(somecloud_type):
+    '''
+    If this test fails, that means that read-only fields are showing
+    up in the activity stream serialization of an instance.
+
+    That _probably_ means that you just connected a new model to the
+    activity_stream_registrar, but did not add its serializer to
+    the model->serializer mapping.
+    '''
+    from awx.main.signals import model_serializer_mapping
+    from awx.main.registrar import activity_stream_registrar
+
+    for Model in activity_stream_registrar.models:
+        assert 'modified' not in get_allowed_fields(Model(), model_serializer_mapping), Model