diff --git a/DependencyInjection/OpenSkySitemapExtension.php b/DependencyInjection/OpenSkySitemapExtension.php
index 849889d..aadce16 100644
--- a/DependencyInjection/OpenSkySitemapExtension.php
+++ b/DependencyInjection/OpenSkySitemapExtension.php
@@ -34,8 +34,9 @@ public function load(array $configs, ContainerBuilder $container)
         $loader->load('sitemap.xml');
 
         $defaults = $container->getParameter('opensky.sitemap.defaults');
+        $properties = array_merge(array('changefreq', 'priority', 'lastmod'), $container->getParameter('opensky.sitemap.properties'));
         foreach ($configs as $config) {
-            foreach (array('changefreq', 'priority', 'lastmod') as $prop) {
+            foreach ($properties as $prop) {
                 if (isset($config['default_' . $prop])) {
                     $defaults[$prop] = $config['default_' . $prop];
                 }
@@ -53,4 +54,4 @@ public function getAlias()
     {
         return 'opensky_sitemap';
     }
-}
\ No newline at end of file
+}
diff --git a/Dumper/Doctrine/ODM/MongoDB.php b/Dumper/Doctrine/ODM/MongoDB.php
index b247e8f..6374ec4 100644
--- a/Dumper/Doctrine/ODM/MongoDB.php
+++ b/Dumper/Doctrine/ODM/MongoDB.php
@@ -19,9 +19,6 @@ class MongoDB implements Dumper
      */
     public function dump(Sitemap $sitemap)
     {
-        // remove the old ones first...
-        $this->getDocumentCollection($sitemap)->remove(array());
-
         // now flush the new ones
         $dm = $this->getDocumentManager($sitemap);
         $dm->flush(null, array('safe' => true));
diff --git a/Event/.SitemapEvent.php.swp b/Event/.SitemapEvent.php.swp
new file mode 100644
index 0000000..5316e60
Binary files /dev/null and b/Event/.SitemapEvent.php.swp differ
diff --git a/Event/SitemapEvent.php b/Event/SitemapEvent.php
new file mode 100644
index 0000000..7faadfe
--- /dev/null
+++ b/Event/SitemapEvent.php
@@ -0,0 +1,25 @@
+<?php
+
+namespace OpenSky\Bundle\SitemapBundle\Event;
+
+use Symfony\Component\EventDispatcher\Event;
+
+class SitemapEvent extends Event
+{
+    protected $arguments;
+
+    public function __construct(array $arguments)
+    {
+        $this->arguments = $arguments;
+    }
+
+    public function get($argument)
+    {
+        return $this->arguments[$argument];
+    }
+
+    public function has($argument)
+    {
+        return isset($this->arguments[$argument]);
+    }
+}
diff --git a/Events.php b/Events.php
new file mode 100644
index 0000000..ae7830f
--- /dev/null
+++ b/Events.php
@@ -0,0 +1,10 @@
+<?php
+
+namespace OpenSky\Bundle\SitemapBundle;
+
+final class Events
+{
+    const OPENSKY_SITEMAP_CREATE = 'opensky.sitemap.create';
+    const OPENSKY_SITEMAP_UPDATE = 'opensky.sitemap.update';
+    const OPENSKY_SITEMAP_DELETE = 'opensky.sitemap.delete';
+}
diff --git a/Listener/SitemapListener.php b/Listener/SitemapListener.php
index fdebdc5..40829ae 100644
--- a/Listener/SitemapListener.php
+++ b/Listener/SitemapListener.php
@@ -50,7 +50,7 @@ public function update(Event $event)
         $lastmod = $url->getLastmod();
 
         $url->setLastmod($time);
-        $url->setChangefreq($this->getChangefreq($time->diff(\DateTime::createFromFormat(Url::LASTMOD_FORMAT, $lastmod))));
+        $url->setChangefreq($this->getChangefreq($time->diff(\DateTime::createFromFormat(Url::LASTMOD_FORMAT, $lastmod->format(Url::LASTMOD_FORMAT)))));
 
         $this->dump($this->sitemap);
     }
@@ -66,6 +66,21 @@ public function create(Event $event)
         $this->dump($this->sitemap);
     }
 
+    public function delete(Event $event)
+    {
+        $urlLoc = $event->get('loc');
+
+        if (!$this->sitemap->has($urlLoc)) {
+            throw new Exception\OutOfBoundsException('Url ' . $urlLoc . ' could not be found.');
+        }
+
+        $url = $this->sitemap->get($urlLoc);
+
+        $this->sitemap->delete($url);
+
+        $this->dump($this->sitemap);
+    }
+
     protected function getChangefreq(\DateInterval $interval)
     {
         return ($interval->y >= 1) ? Url::YEARLY : (($interval->m >= 1) ? Url::MONTHLY : (($interval->d >= 7) ? Url::WEEKLY : Url::DAILY));
@@ -76,4 +91,4 @@ protected function dump(Sitemap $sitemap)
         $this->dumper->dump($sitemap);
     }
 
-}
\ No newline at end of file
+}
diff --git a/Resources/config/sitemap.xml b/Resources/config/sitemap.xml
index caf01e0..396a57a 100644
--- a/Resources/config/sitemap.xml
+++ b/Resources/config/sitemap.xml
@@ -15,6 +15,7 @@
         <parameter key="opensky.sitemap.template.engine">twig</parameter>
         <parameter key="opensky.sitemap.defaults" type="collection" />
         <parameter key="opensky.sitemap.providers" type="collection" />
+        <parameter key="opensky.sitemap.properties" type="collection" />
     </parameters>
 
     <services>
@@ -22,6 +23,7 @@
         <service id="opensky.sitemap.sitemap" class="%opensky.sitemap.class%">
             <argument type="service" id="opensky.sitemap.sitemap.storage" />
             <argument>%opensky.sitemap.defaults%</argument>
+            <argument>%opensky.sitemap.properties%</argument>
             <call method="setUrlClass">
                 <argument>%opensky.sitemap.url.class%</argument>
             </call>
@@ -36,10 +38,11 @@
             </argument>
         </service>
         <service id="opensky.sitemap.listener" class="%opensky.sitemap.listener.class%">
-            <tag name="kernel.listener" event="opensky.sitemap.update" method="update" />
-            <tag name="kernel.listener" event="opensky.sitemap.create" method="create" />
+            <tag name="kernel.event_listener" event="opensky.sitemap.update" method="update" />
+            <tag name="kernel.event_listener" event="opensky.sitemap.create" method="create" />
+            <tag name="kernel.event_listener" event="opensky.sitemap.delete" method="delete" />
             <argument type="service" id="opensky.sitemap.sitemap" />
             <argument type="service" id="opensky.sitemap.dumper" />
         </service>
     </services>
-</container>
\ No newline at end of file
+</container>
diff --git a/Resources/views/Sitemap/sitemap.xml.twig b/Resources/views/Sitemap/sitemap.xml.twig
index aba407c..89442f3 100644
--- a/Resources/views/Sitemap/sitemap.xml.twig
+++ b/Resources/views/Sitemap/sitemap.xml.twig
@@ -10,4 +10,4 @@
             </url>
         {% endfor %}
     </urlset>
-{% endspaceless %}
\ No newline at end of file
+{% endspaceless %}
diff --git a/Sitemap/Sitemap.php b/Sitemap/Sitemap.php
index f901d0d..d5e8431 100644
--- a/Sitemap/Sitemap.php
+++ b/Sitemap/Sitemap.php
@@ -22,6 +22,10 @@ class Sitemap
      * @var array
      */
     protected $defaults = array();
+    /**
+     * @var array
+     */
+    protected $properties = array();
     /**
      * @var OpenSky\Bundle\SitemapBundle\Sitemap\Storage\Storage
      */
@@ -31,10 +35,11 @@ class Sitemap
      * @param OpenSky\Bundle\SitemapBundle\Sitemap\Storage\Storage $storage
      * @param array $defaults
      */
-    public function __construct(Storage $storage, array $defaults = array())
+    public function __construct(Storage $storage, array $defaults = array(), array $properties = array())
     {
         $this->storage = $storage;
-        foreach (array('changefreq', 'priority', 'lastmod') as $prop) {
+        $this->properties = array_merge(array('changefreq', 'priority', 'lastmod'), $properties);
+        foreach ($this->properties as $prop) {
             if (isset($defaults[$prop])) {
                 $this->defaults[$prop] = $defaults[$prop];
             }
@@ -68,7 +73,7 @@ public function add($loc, array $info)
         $info     = array_merge($this->defaults, $info);
         $urlClass = $this->getUrlClass();
         $url      = new $urlClass($loc);
-        foreach (array('changefreq', 'priority', 'lastmod') as $prop) {
+        foreach ($this->properties as $prop) {
             if (isset($info[$prop])) {
                 $url->{'set' . ucfirst($prop)}($info[$prop]);
             }
@@ -77,6 +82,11 @@ public function add($loc, array $info)
         return $url;
     }
 
+    public function delete($url)
+    {
+        $this->storage->remove($url);
+    }
+
     /**
      * @param string $loc
      * @return OpenSky\Bundle\SitemapBundle\Sitemap\Url|null
@@ -122,4 +132,4 @@ public function getStorage()
         return $this->storage;
     }
 
-}
\ No newline at end of file
+}
diff --git a/Sitemap/Storage/Doctrine/ODM/MongoDB.php b/Sitemap/Storage/Doctrine/ODM/MongoDB.php
index c713f37..bf9be9a 100644
--- a/Sitemap/Storage/Doctrine/ODM/MongoDB.php
+++ b/Sitemap/Storage/Doctrine/ODM/MongoDB.php
@@ -82,6 +82,16 @@ public function save(Url $url)
         $this->dm->persist($url);
     }
 
+    /**
+     * Removes a Url in DocumentManager, does not call flush
+     *
+     * @param OpenSky\Bundle\SitemapBundle\Sitemap\Url $url
+     */
+    public function remove(Url $url)
+    {
+        $this->dm->remove($url);
+    }
+
     /**
      * @return Doctrine\ODM\MongoDB\DocumentManager
      */
@@ -102,4 +112,4 @@ private function getSkip($page)
     {
         return ((int) $page - 1) * self::PAGE_LIMIT;
     }
-}
\ No newline at end of file
+}
diff --git a/composer.json b/composer.json
index 709d8cf..e793dee 100644
--- a/composer.json
+++ b/composer.json
@@ -7,7 +7,7 @@
     "license": "MIT",
     "require": {
         "php": ">=5.3.0",
-        "symfony/framework-bundle": ">=2.1.0,<2.3-dev"
+        "symfony/framework-bundle": ">=2.1.0,<2.7-dev"
     },
     "autoload": {
         "psr-0": { "OpenSky\\Bundle\\SitemapBundle": "" }