diff --git a/README.md b/README.md
index 18b5a0b..d6985bb 100644
--- a/README.md
+++ b/README.md
@@ -41,7 +41,7 @@ class Note extends ODM\Document\Document
 }
 
 /* Initialize connection */
-$dbal = new ODM\DBAL('127.0.0.1', '27017', 'test2');
+$dbal = new ODM\DBAL('127.0.0.1', '27017', 'test');
 $factory = new ODM\DocumentMapper\DataMapperFactory($dbal);
 
 /* Initialize DataMapper for your Document */
diff --git a/composer.json b/composer.json
index 83f091a..aad52ca 100644
--- a/composer.json
+++ b/composer.json
@@ -3,7 +3,8 @@
     "description": "mongo odm",
     "type": "library",
     "require": {
-        "mongodb/mongodb": "^1.1"
+        "mongodb/mongodb": "^1.1",
+        "php": "7.*"
     },
     "autoload": {
         "psr-4": { "ODM\\": "src/" }
diff --git a/src/Instantiator/Instantiator.php b/src/Instantiator/Instantiator.php
index 21ecb9e..873aee8 100644
--- a/src/Instantiator/Instantiator.php
+++ b/src/Instantiator/Instantiator.php
@@ -4,9 +4,6 @@
 
 class Instantiator
 {
-    const SERIALIZATION_FORMAT_USE_UNSERIALIZER   = 'C';
-    const SERIALIZATION_FORMAT_AVOID_UNSERIALIZER = 'O';
-
     /**
      * @param string $class_name
      * @return mixed