diff --git a/WeChat/Contracts/Tools.php b/WeChat/Contracts/Tools.php
index b919e5c..fda7e90 100644
--- a/WeChat/Contracts/Tools.php
+++ b/WeChat/Contracts/Tools.php
@@ -150,7 +150,7 @@ class Tools
         $entity = libxml_disable_entity_loader(true);
         $data = (array)simplexml_load_string($xml, 'SimpleXMLElement', LIBXML_NOCDATA);
         libxml_disable_entity_loader($entity);
-        return json_decode(self::arr2json($data), true);
+        return json_decode(json_encode($data), true);
     }
 
     /**
@@ -162,7 +162,7 @@ class Tools
     {
         return preg_replace_callback('/\\\\u([0-9a-f]{4})/i', function ($matches) {
             return mb_convert_encoding(pack("H*", $matches[1]), "UTF-8", "UCS-2BE");
-        }, ($jsonData = json_encode($data)) == '[]' ? '{}' : $jsonData);
+        }, ($json = json_encode($data)) == '[]' ? '{}' : $json);
     }
 
     /**
diff --git a/composer.json b/composer.json
index 0e8cfa4..d8ee7c1 100644
--- a/composer.json
+++ b/composer.json
@@ -23,7 +23,10 @@
     "php": ">=5.4",
     "ext-json": "*",
     "ext-curl": "*",
-    "ext-openssl": "*"
+    "ext-libxml": "*",
+    "ext-openssl": "*",
+    "ext-mbstring": "*",
+    "ext-simplexml": "*"
   },
   "autoload": {
     "classmap": [