diff --git a/packages/backend/src/remote/activitypub/models/person.ts b/packages/backend/src/remote/activitypub/models/person.ts
index e354f8811..4b9218deb 100644
--- a/packages/backend/src/remote/activitypub/models/person.ts
+++ b/packages/backend/src/remote/activitypub/models/person.ts
@@ -87,7 +87,7 @@ async function validateActor(x: IObject, resolver: Resolver): Promise<IActor> {
 	}
 
 	// unify different sharedInbox places
-	x.sharedInbox = x.sharedInbox ?? x.endpoints?.sharedInbox;
+	x.sharedInbox = x.sharedInbox ?? x.endpoints?.sharedInbox ?? null;
 	if (x.sharedInbox != null) {
 		// check that sharedInbox is a valid and absolute URL
 		try {