diff --git a/portnums.proto b/portnums.proto
index 25612b1..964be66 100644
--- a/portnums.proto
+++ b/portnums.proto
@@ -65,6 +65,11 @@ enum PortNum {
     */
     NODEINFO_APP = 4;
 
+    /** Provides a 'ping' service that replies to any packet it receives.  Also this serves as a
+    small example plugin.
+    */
+    REPLY_APP = 32;
+
     /** 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;