diff --git a/btlejack/pcap.py b/btlejack/pcap.py
index 3ca1f92..ccd4d46 100755
--- a/btlejack/pcap.py
+++ b/btlejack/pcap.py
@@ -133,7 +133,7 @@ def payload(self, aa, packet):
         payload_header = pack(
             '<BbbBIH',
             packet[2],
-            -40,
+            -packet[3],
             -100,
             0,
             aa,