diff --git a/packages/backend/src/remote/activitypub/models/person.ts b/packages/backend/src/remote/activitypub/models/person.ts
index 8f17cfae8b..813e4c81c5 100644
--- a/packages/backend/src/remote/activitypub/models/person.ts
+++ b/packages/backend/src/remote/activitypub/models/person.ts
@@ -554,7 +554,7 @@ export async function updatePerson(
 		{
 			followerSharedInbox:
 				person.sharedInbox ||
-				(person.endpoints ? person.endpoints.sharedInbox : undefined),
+				(person.endpoints ? person.endpoints.sharedInbox : null),
 		},
 	);