diff --git a/src/Extension/TransformTo.php b/src/Extension/TransformTo.php
index 6fd1dc6..6163931 100644
--- a/src/Extension/TransformTo.php
+++ b/src/Extension/TransformTo.php
@@ -13,6 +13,8 @@ class TransformTo implements ExtensionInterface
 {
     /**
      * Transforms the data to given class via setter and getter methods.
+     * Important: If you pass the `object` param as string, then the class must
+     * be initializable without constructor arguments.
      *
      * @param Mapping       $mapping The mapping object
      * @param string|object $object  The class name or an object
diff --git a/src/Factory.php b/src/Factory.php
index 1a158c8..4f27b5a 100644
--- a/src/Factory.php
+++ b/src/Factory.php
@@ -18,6 +18,7 @@ public function __construct(array $extensions = [])
     {
         $this->extensions = array_merge([
             new \Mapped\Extension\Transform,
+            new \Mapped\Extension\TransformTo,
             new \Mapped\Extension\Validation,
             new \Mapped\Extension\Multiple,
             new \Mapped\Extension\Optional,
diff --git a/tests/Extension/TransformToTest.php b/tests/Extension/TransformToTest.php
index a8b1a0a..5d8b51f 100644
--- a/tests/Extension/TransformToTest.php
+++ b/tests/Extension/TransformToTest.php
@@ -10,7 +10,7 @@ class TransformToTest extends \PHPUnit_Framework_TestCase
 {
     public function testA()
     {
-        $factory = new Factory([new \Mapped\Extension\TransformTo]);
+        $factory = new Factory;
 
         $mapping = $factory->mapping([
             'title'  => $factory->string(),
@@ -33,7 +33,7 @@ public function testA()
 
     public function testB()
     {
-        $factory = new Factory([new \Mapped\Extension\TransformTo]);
+        $factory = new Factory;
 
         $mapping = $factory->mapping([
             'title'  => $factory->string(),
@@ -49,9 +49,9 @@ public function testB()
 
     public function testC()
     {
-        $factory = new Factory([new \Mapped\Extension\TransformTo]);
-
+        $factory = new Factory;
         $book = new Book;
+
         $mapping = $factory->mapping([
             'title'  => $factory->string(),
             'author' => $factory->string(),
@@ -68,7 +68,7 @@ public function testC()
 
     public function testD()
     {
-        $factory = new Factory([new \Mapped\Extension\TransformTo]);
+        $factory = new Factory;
         $user = new User('a', 'b');
 
         $mapping = $factory->mapping([