diff --git a/FilesystemMap.php b/FilesystemMap.php
index 5cf9de1..d64117d 100644
--- a/FilesystemMap.php
+++ b/FilesystemMap.php
@@ -13,7 +13,7 @@ class FilesystemMap
      *
      * @var array
      */
-    private $map;
+    protected $map;
 
     /**
      * Instanciates a new filesystem map
diff --git a/Resources/config/gaufrette.xml b/Resources/config/gaufrette.xml
index c901c08..8d67963 100644
--- a/Resources/config/gaufrette.xml
+++ b/Resources/config/gaufrette.xml
@@ -4,6 +4,9 @@
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
 
+   	<parameters>
+	    <parameter key="knp_gaufrette.filesystem_map.class">Knp\Bundle\GaufretteBundle\FilesystemMap</parameter>
+    </parameters>
     <services>
         <service id="knp_gaufrette.filesystem" class="Gaufrette\Filesystem" abstract="true">
             <argument /><!-- The Adapter -->
@@ -31,7 +34,7 @@
             <argument /><!-- prefix -->
             <argument /><!-- ttl -->
         </service>
-        <service id="knp_gaufrette.filesystem_map" class="Knp\Bundle\GaufretteBundle\FilesystemMap">
+        <service id="knp_gaufrette.filesystem_map" class="%knp_gaufrette.filesystem_map.class%">
             <argument /> <!-- map of filesystems -->
         </service>
     </services>