diff --git a/apns.py b/apns.py
index 065b64f..a1a8b68 100644
--- a/apns.py
+++ b/apns.py
@@ -39,6 +39,7 @@ COMMANDS = {
     0x8: "ConnectResponse",
     0x9: "PushTopics",
     0x0A: "PushNotification",
+    0x0B: "Acknowledge",
 }
 
 class Payload:
diff --git a/demo.py b/demo.py
index 601b22c..a6b90e3 100644
--- a/demo.py
+++ b/demo.py
@@ -23,11 +23,16 @@ expiry = expiry.to_bytes(4, "big")
 # Current time in UNIX nano epoch
 import time
 now = int(time.time() * 1000).to_bytes(8, "big")
-payload = apns.Payload(0x0a, apns.Fields({1: sha1(b"com.apple.madrid").digest(), 2: conn2.token, 3: b"Hello World!", 5: expiry, 6: now, 7: 0x00.to_bytes()}))
+
+payload = apns.Payload(0x0a, apns.Fields({1: sha1(b"com.apple.madrid").digest(), 2: conn2.token, 3: b"Hello World!", 4: 0x00.to_bytes(), 5: expiry, 6: now, 7: 0x00.to_bytes()}))
 conn1.sock.write(payload.to_bytes())
 
 print("Waiting for response...")
 
 # Check if the notification was sent
+resp = apns.Payload.from_stream(conn1.sock)
+print(resp)
+
+# Read the message from the other connection
 resp = apns.Payload.from_stream(conn2.sock)
 print(resp)
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