diff --git a/appstats.js b/appstats.js
index 139a9b8..e50b642 100644
--- a/appstats.js
+++ b/appstats.js
@@ -9,7 +9,6 @@
  */
 
 const async = require('async');
-const util = require('util');
 const moment = require('moment');
 const parse = require('parse-key-value');
 const azureStorage = require('azure-storage');
@@ -293,7 +292,16 @@ class AzureCollectionStats {
                         return callback();
                     });
                 }, function() {
-                    return processed < metadata.approximateMessageCount;
+                    const cb = arguments[arguments.length - 1];
+                    const args = Array.prototype.slice.call(arguments, 0, arguments.length - 1);
+                    const f = function() {
+                        return processed < metadata.approximateMessageCount;
+                    };
+                    try {
+                        cb(null, f.apply(this, args));
+                    } catch (e) {
+                        cb(e, null);
+                    }
                 }, function() {
                     if (!resultError) {
                         return callback(null, resultStats);
diff --git a/package.json b/package.json
index c0dacef..8b1210b 100644
--- a/package.json
+++ b/package.json
@@ -19,7 +19,7 @@
   },
   "dependencies": {
     "al-collector-js": "git://github.com/alertlogic/al-collector-js#master",
-    "async": "^2.6.1",
+    "async": "^3.0.0",
     "azure": "^2.3.1-preview",
     "parse-key-value": "^1.0.0",
     "path": "^0.12.7"