diff --git a/composer.json b/composer.json
index e3ea17c..07edd94 100644
--- a/composer.json
+++ b/composer.json
@@ -4,8 +4,7 @@
     "license" : "MIT",
 
     "autoload" : {
-        "psr-0" : { "Tacker\\" : "src" },
-        "files" : ["src/Tacker/functions.php"]
+        "psr-0" : { "Tacker\\" : "src" }
     },
 
     "require" : {
diff --git a/src/Tacker/Loader/NormalizerLoader.php b/src/Tacker/Loader/NormalizerLoader.php
index e5653dd..219d5a4 100644
--- a/src/Tacker/Loader/NormalizerLoader.php
+++ b/src/Tacker/Loader/NormalizerLoader.php
@@ -20,7 +20,7 @@ public function load($resource, $type = null)
     {
         $parameters = $this->loader->load($resource, $type);
 
-        return tacker_array_map_recursive($parameters, array($this, 'normalize'));
+        return array_map(array($this, 'normalize'), $parameters);
     }
 
     public function supports($resource, $type = null)
@@ -28,8 +28,12 @@ public function supports($resource, $type = null)
         return $this->loader->supports($resource, $type);
     }
 
-    public function normalize($value)
+    private function normalize($value)
     {
-        return is_string($value) ? $this->normalizer->normalize($value) : $value;
+        if (is_array($value)) {
+            return array_map(array($this, 'normalize'), $value);
+        }
+
+        return $this->normalizer->normalize($value);
     }
 }
diff --git a/src/Tacker/functions.php b/src/Tacker/functions.php
deleted file mode 100644
index 53df2c3..0000000
--- a/src/Tacker/functions.php
+++ /dev/null
@@ -1,11 +0,0 @@
-<?php
-
-function tacker_array_map_recursive(array $array, $f) {
-    $map = array();
-
-    foreach ($array as $k => $v) {
-        $map[$k] = is_array($v) ? tacker_array_map_recursive($v, $f) : call_user_func($f, $v);
-    }
-
-    return $map;
-}