Computed property in handlebars template

computed

This is the computed property, which depends on an image array, the product.images

smallImages: function() {
	"use strict";
	var smalls = product.images.map(function(original){
		return original + "-small.png";
	});
	return smalls;
}.property('product.images').cacheable(),

What I need, is something like this in my template:

{{#each image in smallImages}}
<li class="small-image">
<img src="{{image}}"/>
</li>
{{/each}}

But here that computed property looks undefined.