diff --git a/src/workos/types/user_management/organization_membership.py b/src/workos/types/user_management/organization_membership.py
index 5c7bda0f..67ba1f21 100644
--- a/src/workos/types/user_management/organization_membership.py
+++ b/src/workos/types/user_management/organization_membership.py
@@ -1,4 +1,5 @@
 from typing import Any, Literal, Mapping, Optional, Sequence
+
 from typing_extensions import TypedDict
 
 from workos.types.workos_model import WorkOSModel
@@ -21,6 +22,6 @@ class OrganizationMembership(WorkOSModel):
     role: OrganizationMembershipRole
     roles: Optional[Sequence[OrganizationMembershipRole]] = None
     status: LiteralOrUntyped[OrganizationMembershipStatus]
-    custom_attributes: Mapping[str, Any]
+    custom_attributes: Mapping[str, Any] = {}
     created_at: str
     updated_at: str
diff --git a/tests/test_events.py b/tests/test_events.py
index 6bc003c3..d516d506 100644
--- a/tests/test_events.py
+++ b/tests/test_events.py
@@ -4,6 +4,7 @@
 from tests.utils.fixtures.mock_event import MockEvent
 from tests.utils.syncify import syncify
 from workos.events import AsyncEvents, Events, EventsListResource
+from workos.types.events import OrganizationMembershipCreatedEvent
 
 
 @pytest.mark.sync_and_async(Events, AsyncEvents)
@@ -40,3 +41,47 @@ def test_list_events(
         assert request_kwargs["method"] == "get"
         assert request_kwargs["params"] == {"events": ["dsync.activated"], "limit": 10}
         assert events.dict() == mock_events
+
+    def test_list_events_organization_membership_missing_custom_attributes(
+        self,
+        module_instance: Union[Events, AsyncEvents],
+        capture_and_mock_http_client_request,
+    ):
+        mock_response = {
+            "object": "list",
+            "data": [
+                {
+                    "object": "event",
+                    "id": "event_01234",
+                    "event": "organization_membership.created",
+                    "data": {
+                        "object": "organization_membership",
+                        "id": "om_01234",
+                        "user_id": "user_01234",
+                        "organization_id": "org_01234",
+                        "role": {"slug": "member"},
+                        "status": "active",
+                        "created_at": "2024-01-01T00:00:00.000Z",
+                        "updated_at": "2024-01-01T00:00:00.000Z",
+                    },
+                    "created_at": "2024-01-01T00:00:00.000Z",
+                }
+            ],
+            "list_metadata": {
+                "after": None,
+            },
+        }
+
+        capture_and_mock_http_client_request(
+            http_client=module_instance._http_client,
+            status_code=200,
+            response_dict=mock_response,
+        )
+
+        events: EventsListResource = syncify(
+            module_instance.list_events(events=["organization_membership.created"])
+        )
+
+        event = events.data[0]
+        assert isinstance(event, OrganizationMembershipCreatedEvent)
+        assert event.data.custom_attributes == {}