diff --git a/src/lib/handlers/ack.ts b/src/lib/handlers/ack.ts
index 83f902966..45851686c 100644
--- a/src/lib/handlers/ack.ts
+++ b/src/lib/handlers/ack.ts
@@ -144,7 +144,7 @@ const handleAck: PacketHandler = (client, packet) => {
 			delete client.outgoing[messageId]
 			client.messageIdProvider.deallocate(messageId)
 			client['_invokeStoreProcessingQueue']()
-			cb(null)
+			cb(null, packet)
 			break
 		}
 		default:
diff --git a/test/abstract_client.ts b/test/abstract_client.ts
index d4441318a..effa9ac54 100644
--- a/test/abstract_client.ts
+++ b/test/abstract_client.ts
@@ -1974,7 +1974,7 @@ export default function abstractTest(server, config, ports) {
 			client.once('connect', () => {
 				// callback args can be typed
 				client.unsubscribe(topic, (_, packet?: mqtt.Packet) => {
-					assert.isUndefined(packet)
+					assert.isDefined(packet)
 					client.end(true, done)
 				})
 			})