diff --git a/lib/ext/async.js b/lib/ext/async.js
index 453c112..f96eab8 100644
--- a/lib/ext/async.js
+++ b/lib/ext/async.js
@@ -2,11 +2,12 @@
 
 'use strict';
 
-var toArray    = require('es5-ext/lib/Array/from')
-  , last       = require('es5-ext/lib/Array/prototype/last')
-  , forEach    = require('es5-ext/lib/Object/for-each')
-  , isCallable = require('es5-ext/lib/Object/is-callable')
-  , nextTick   = require('next-tick')
+var toArray     = require('es5-ext/lib/Array/from')
+  , last        = require('es5-ext/lib/Array/prototype/last')
+  , isArguments = require('es5-ext/lib/Function/is-arguments')
+  , forEach     = require('es5-ext/lib/Object/for-each')
+  , isCallable  = require('es5-ext/lib/Object/is-callable')
+  , nextTick    = require('next-tick')
 
   , isArray = Array.isArray, slice = Array.prototype.slice
   , apply = Function.prototype.apply;
@@ -101,7 +102,7 @@ require('../_base').ext.async = function (ignore, conf) {
 		// If false, we don't have value yet, so we assume that intention is not
 		// to memoize this call. After value is obtained we don't cache it but
 		// gracefully pass to callback
-		if (!isArray(cache[id])) {
+		if (isArguments(cache[id])) {
 			conf.emit('purgeasync', id);
 			delete cache[id];
 		}
diff --git a/test/ext/async.js b/test/ext/async.js
index 833f121..732f36d 100644
--- a/test/ext/async.js
+++ b/test/ext/async.js
@@ -3,6 +3,8 @@
 var memoize  = require('../../lib')
   , nextTick = require('next-tick');
 
+require('../../lib/ext/dispose');
+
 module.exports = function () {
 	return {
 		"Regular": {
@@ -85,7 +87,7 @@ module.exports = function () {
 					return u;
 				};
 
-				mfn = memoize(fn, { async: true });
+				mfn = memoize(fn, { async: true, dispose: a.never });
 
 				a(mfn(3, 7, function (err, res) {
 					a.deep([err, res], [e, undefined], "Result #1");