Math functions in angular brackets

Semo of math function not working in angular binding

HTML

<script src="//ajax.googleapis.com/ajax/libs/angularjs/1.0.2/angular.min.js"></script>
<div ng-app="miniapp">
    <div ng-controller="Ctrl">
        <p>This works: [ {{0.5}} ]</p>
        <p>This now works: [ {{0.5 | ceil}} ]</p>
    </div>    
</div>

JavaScript

var app = angular.module('miniapp', []);

app.filter('ceil', function() {
  return function(input) {
    return Math.ceil(input);
  };
});

function Ctrl($scope) {}