diff --git a/src/Stash/Driver/FileSystem.php b/src/Stash/Driver/FileSystem.php
index 5609a350..b308f746 100644
--- a/src/Stash/Driver/FileSystem.php
+++ b/src/Stash/Driver/FileSystem.php
@@ -68,7 +68,8 @@ class FileSystem implements DriverInterface
     protected $defaultOptions = array('filePermissions' => 0660,
                                       'dirPermissions' => 0770,
                                       'dirSplit' => 2,
-                                      'memKeyLimit' => 20
+                                      'memKeyLimit' => 20,
+                                      'keyHashFunction' => 'md5'
     );
 
     public function __construct(array $options = array())
@@ -91,6 +92,13 @@ public function __construct(array $options = array())
             $options['memKeyLimit'] = 0;
         }
 
+        if (function_exists($options['keyHashFunction'])) {
+            $this->keyHashFunction = $options['keyHashFunction'];
+        }
+        else {
+            $this->keyHashFunction = 'md5';
+        }
+
         $this->memStoreLimit = (int)$options['memKeyLimit'];
 
         $this->checkFileSystemPermissions();
@@ -248,7 +256,7 @@ protected function makePath($key = null)
             $pathPieces = array();
             $path = $basePath;
             $len = floor(32 / $this->directorySplit);
-            $key = \Stash\Utilities::normalizeKeys($key);
+            $key = \Stash\Utilities::normalizeKeys($key, $this->keyHashFunction);
 
             foreach ($key as $index => $value) {
                 if (strpos($value, '@') === 0) {