diff --git a/src/packet/packet.js b/src/packet/packet.js
index 8de54895..4a0ba0f8 100644
--- a/src/packet/packet.js
+++ b/src/packet/packet.js
@@ -235,7 +235,7 @@ module.exports = {
             break;
           }
         }
-        real_packet_length = mypos2;
+        real_packet_length = mypos2 - mypos;
         // 4.2.2.3. Five-Octet Lengths
       } else {
         mypos++;