diff --git a/chapter-19/arena.js b/chapter-19/arena.js
index 1e516e5..4455c83 100644
--- a/chapter-19/arena.js
+++ b/chapter-19/arena.js
@@ -8,6 +8,10 @@ var instructions = [
   '/jsp snowball'
 ];
 
+// Added reference to prevent persist() object thrashing when called externally
+function getArenas() {
+  return arenas;
+
 function snowballArena() {
   var arena = {};
   
@@ -67,4 +71,5 @@ function snowballArena() {
 
 Drone.extend( snowballArena );
 
+exports.getArenas = getArenas;
 
diff --git a/chapter-19/command.js b/chapter-19/command.js
index c47875d..81f9255 100644
--- a/chapter-19/command.js
+++ b/chapter-19/command.js
@@ -4,7 +4,7 @@ var utils = require('utils');
 var cm = Packages.net.canarymod;
 var cmLocation = cm.api.world.position.Location;
 var game = require('./game');
-var arenas = persist('snowball-arenas', []);
+
 
 function snowball( params, sender ){
   var duration = 60; // seconds
@@ -17,6 +17,9 @@ function snowball( params, sender ){
   var teams = {red: [], blue:[], yellow:[]};
   var spawns = [];
   var spawn = null;
+// use local arenas object reference from arenas.js, rather than creating another global one. Seemed to cause issues when it was global.
+  var aplugin = require('./arena');
+  var arenas = aplugin.getArenas();
 
   for ( i = 0; i < arenas.length; i++ ) {
     arena = arenas[i];