diff --git a/portnums.proto b/portnums.proto
index 422b6ca..a81fa84 100644
--- a/portnums.proto
+++ b/portnums.proto
@@ -72,7 +72,17 @@ enum PortNum {
     /** Used for the python IP tunnel feature */
     IP_TUNNEL_APP = 33;
 
+    /** Provides a hardware serial interface to send and receive from the Meshtastic network.
+    Connect to the RX/TX pins of a device with 38400 8N1. Packets received from the Meshtastic
+    network is forwarded to the RX pin while sending a packet to TX will go out to the Mesh
+    network. Maximum packet size of 240 bytes.
+    
+    Plugin is disabled by default can be turned on by setting SERIALPLUGIN_ENABLED = 1 in
+    SerialPlugh.cpp.
+    */
+    SERIAL_APP = 64;
+
     /** Private applications should use portnums >= 256.  To simplify initial development and testing you can use "PRIVATE_APP"
      in your code without needing to rebuild protobuf files (via bin/regin_protos.sh) */
     PRIVATE_APP = 256;
-  }
\ No newline at end of file
+  }