diff --git a/composer.json b/composer.json
index ac219ee..8c4507d 100644
--- a/composer.json
+++ b/composer.json
@@ -6,6 +6,6 @@
         "php": ">=7.4"
     },
     "autoload": {
-        "classmap": ["config.inc.php"]
+        "classmap": ["config.inc.php", "msgpack_custom.inc.php"]
     }
 }
diff --git a/msgpack_custom.inc.php b/msgpack_custom.inc.php
index b8c6833..90da05a 100644
--- a/msgpack_custom.inc.php
+++ b/msgpack_custom.inc.php
@@ -1,10 +1,10 @@
 <?php
 
-class MessagePackCustom extends MessagePack\Packer 
+class MessagePackCustom extends \MessagePack\Packer 
 {
   public function __construct()
   {
-      parent::__construct(MessagePack\PackOptions::FORCE_STR);
+      parent::__construct(\MessagePack\PackOptions::FORCE_STR);
   }
 
   public function packStr($str)