diff --git a/packages/backend/src/core/QueueService.ts b/packages/backend/src/core/QueueService.ts
index c999e73169..58c0953631 100644
--- a/packages/backend/src/core/QueueService.ts
+++ b/packages/backend/src/core/QueueService.ts
@@ -121,7 +121,7 @@ export class QueueService {
 				content,
 				to: d[0],
 				isSharedInbox: d[1],
-			} as DeliverJobData,
+			},
 			opts,
 		})));
 
diff --git a/packages/backend/src/server/ActivityPubServerService.ts b/packages/backend/src/server/ActivityPubServerService.ts
index f87cb14dcf..a1dcc4f484 100644
--- a/packages/backend/src/server/ActivityPubServerService.ts
+++ b/packages/backend/src/server/ActivityPubServerService.ts
@@ -162,7 +162,13 @@ export class ActivityPubServerService {
 			}
 		}
 
-		this.queueService.inbox(request.body as IActivity, signature);
+		const activity = request.body as IActivity;
+		if (!activity.type || !signature.keyId) {
+			reply.code(400);
+			return;
+		}
+
+		this.queueService.inbox(activity, signature);
 
 		reply.code(202);
 	}