diff --git a/Structural/Decorator/Decorator.php b/Structural/Decorator/Decorator.php
deleted file mode 100644
index 0b8fde3..0000000
--- a/Structural/Decorator/Decorator.php
+++ /dev/null
@@ -1,31 +0,0 @@
-<?php
-
-namespace DesignPatterns\Structural\Decorator;
-
-/**
- * the Decorator MUST implement the RendererInterface contract, this is the key-feature
- * of this design pattern. If not, this is no longer a Decorator but just a dumb
- * wrapper.
- */
-
-/**
- * class Decorator.
- */
-abstract class Decorator implements RendererInterface
-{
-    /**
-     * @var RendererInterface
-     */
-    protected $wrapped;
-
-    /**
-     * You must type-hint the wrapped component :
-     * It ensures you can call renderData() in the subclasses !
-     *
-     * @param RendererInterface $wrappable
-     */
-    public function __construct(RendererInterface $wrappable)
-    {
-        $this->wrapped = $wrappable;
-    }
-}
diff --git a/Structural/Decorator/JsonRenderer.php b/Structural/Decorator/JsonRenderer.php
new file mode 100644
index 0000000..9cc4066
--- /dev/null
+++ b/Structural/Decorator/JsonRenderer.php
@@ -0,0 +1,11 @@
+<?php
+
+namespace DesignPatterns\Structural\Decorator;
+
+class JsonRenderer extends RendererDecorator
+{
+    public function renderData(): string
+    {
+        return json_encode($this->wrapped->renderData());
+    }
+}
diff --git a/Structural/Decorator/README.rst b/Structural/Decorator/README.rst
index b57a608..c854787 100644
--- a/Structural/Decorator/README.rst
+++ b/Structural/Decorator/README.rst
@@ -25,9 +25,9 @@ Code
 
 You can also find these code on `GitHub`_
 
-RendererInterface.php
+RenderableInterface.php
 
-.. literalinclude:: RendererInterface.php
+.. literalinclude:: RenderableInterface.php
    :language: php
    :linenos:
 
@@ -37,21 +37,21 @@ Webservice.php
    :language: php
    :linenos:
 
-Decorator.php
+RendererDecorator.php
 
-.. literalinclude:: Decorator.php
+.. literalinclude:: RendererDecorator.php
    :language: php
    :linenos:
 
-RenderInXml.php
+XmlRenderer.php
 
-.. literalinclude:: RenderInXml.php
+.. literalinclude:: XmlRenderer.php
    :language: php
    :linenos:
 
-RenderInJson.php
+JsonRenderer.php
 
-.. literalinclude:: RenderInJson.php
+.. literalinclude:: JsonRenderer.php
    :language: php
    :linenos:
 
diff --git a/Structural/Decorator/RenderInJson.php b/Structural/Decorator/RenderInJson.php
deleted file mode 100644
index e950e28..0000000
--- a/Structural/Decorator/RenderInJson.php
+++ /dev/null
@@ -1,16 +0,0 @@
-<?php
-
-namespace DesignPatterns\Structural\Decorator;
-
-class RenderInJson extends Decorator
-{
-    /**
-     * render data as JSON.
-     *
-     * @return string
-     */
-    public function renderData()
-    {
-        return json_encode($this->wrapped->renderData());
-    }
-}
diff --git a/Structural/Decorator/RenderInXml.php b/Structural/Decorator/RenderInXml.php
deleted file mode 100644
index 5afffda..0000000
--- a/Structural/Decorator/RenderInXml.php
+++ /dev/null
@@ -1,24 +0,0 @@
-<?php
-
-namespace DesignPatterns\Structural\Decorator;
-
-class RenderInXml extends Decorator
-{
-    /**
-     * render data as XML.
-     *
-     * @return string
-     */
-    public function renderData()
-    {
-        // do some fancy conversion to xml from array ...
-
-        $doc = new \DOMDocument();
-
-        foreach ($this->wrapped->renderData() as $key => $val) {
-            $doc->appendChild($doc->createElement($key, $val));
-        }
-
-        return $doc->saveXML();
-    }
-}
diff --git a/Structural/Decorator/RenderableInterface.php b/Structural/Decorator/RenderableInterface.php
new file mode 100644
index 0000000..07e11d1
--- /dev/null
+++ b/Structural/Decorator/RenderableInterface.php
@@ -0,0 +1,8 @@
+<?php
+
+namespace DesignPatterns\Structural\Decorator;
+
+interface RenderableInterface
+{
+    public function renderData(): string;
+}
diff --git a/Structural/Decorator/RendererDecorator.php b/Structural/Decorator/RendererDecorator.php
new file mode 100644
index 0000000..e2bd02a
--- /dev/null
+++ b/Structural/Decorator/RendererDecorator.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace DesignPatterns\Structural\Decorator;
+
+/**
+ * the Decorator MUST implement the RendererInterface contract, this is the key-feature
+ * of this design pattern. If not, this is no longer a Decorator but just a dumb
+ * wrapper.
+ */
+abstract class RendererDecorator
+{
+    /**
+     * @var RenderableInterface
+     */
+    protected $wrapped;
+
+    /**
+     * @param RenderableInterface $renderer
+     */
+    public function __construct(RenderableInterface $renderer)
+    {
+        $this->wrapped = $renderer;
+    }
+}
diff --git a/Structural/Decorator/RendererInterface.php b/Structural/Decorator/RendererInterface.php
deleted file mode 100644
index e7b95eb..0000000
--- a/Structural/Decorator/RendererInterface.php
+++ /dev/null
@@ -1,13 +0,0 @@
-<?php
-
-namespace DesignPatterns\Structural\Decorator;
-
-interface RendererInterface
-{
-    /**
-     * render data.
-     *
-     * @return string
-     */
-    public function renderData();
-}
diff --git a/Structural/Decorator/Tests/DecoratorTest.php b/Structural/Decorator/Tests/DecoratorTest.php
index 2878772..563df49 100644
--- a/Structural/Decorator/Tests/DecoratorTest.php
+++ b/Structural/Decorator/Tests/DecoratorTest.php
@@ -4,77 +4,29 @@ namespace DesignPatterns\Structural\Decorator\Tests;
 
 use DesignPatterns\Structural\Decorator;
 
-/**
- * DecoratorTest tests the decorator pattern.
- */
 class DecoratorTest extends \PHPUnit_Framework_TestCase
 {
-    protected $service;
+    /**
+     * @var Decorator\Webservice
+     */
+    private $service;
 
     protected function setUp()
     {
-        $this->service = new Decorator\Webservice(array('foo' => 'bar'));
+        $this->service = new Decorator\Webservice('foobar');
     }
 
     public function testJsonDecorator()
     {
-        // Wrap service with a JSON decorator for renderers
-        $service = new Decorator\RenderInJson($this->service);
-        // Our Renderer will now output JSON instead of an array
-        $this->assertEquals('{"foo":"bar"}', $service->renderData());
+        $service = new Decorator\JsonRenderer($this->service);
+
+        $this->assertEquals('"foobar"', $service->renderData());
     }
 
     public function testXmlDecorator()
     {
-        // Wrap service with a XML decorator for renderers
-        $service = new Decorator\RenderInXml($this->service);
-        // Our Renderer will now output XML instead of an array
-        $xml = '<?xml version="1.0"?><foo>bar</foo>';
-        $this->assertXmlStringEqualsXmlString($xml, $service->renderData());
-    }
+        $service = new Decorator\XmlRenderer($this->service);
 
-    /**
-     * The first key-point of this pattern :.
-     */
-    public function testDecoratorMustImplementsRenderer()
-    {
-        $className = 'DesignPatterns\Structural\Decorator\Decorator';
-        $interfaceName = 'DesignPatterns\Structural\Decorator\RendererInterface';
-        $this->assertTrue(is_subclass_of($className, $interfaceName));
-    }
-
-    /**
-     * Second key-point of this pattern : the decorator is type-hinted.
-     *
-     * @expectedException \PHPUnit_Framework_Error
-     */
-    public function testDecoratorTypeHinted()
-    {
-        if (version_compare(PHP_VERSION, '7', '>=')) {
-            throw new \PHPUnit_Framework_Error('Skip test for PHP 7', 0, __FILE__, __LINE__);
-        }
-
-        $this->getMockForAbstractClass('DesignPatterns\Structural\Decorator\Decorator', array(new \stdClass()));
-    }
-
-    /**
-     * Second key-point of this pattern : the decorator is type-hinted.
-     *
-     * @requires PHP 7
-     * @expectedException TypeError
-     */
-    public function testDecoratorTypeHintedForPhp7()
-    {
-        $this->getMockForAbstractClass('DesignPatterns\Structural\Decorator\Decorator', array(new \stdClass()));
-    }
-
-    /**
-     * The decorator implements and wraps the same interface.
-     */
-    public function testDecoratorOnlyAcceptRenderer()
-    {
-        $mock = $this->createMock('DesignPatterns\Structural\Decorator\RendererInterface');
-        $dec = $this->getMockForAbstractClass('DesignPatterns\Structural\Decorator\Decorator', array($mock));
-        $this->assertNotNull($dec);
+        $this->assertXmlStringEqualsXmlString('<?xml version="1.0"?><content>foobar</content>', $service->renderData());
     }
 }
diff --git a/Structural/Decorator/Webservice.php b/Structural/Decorator/Webservice.php
index 1151672..6715a22 100644
--- a/Structural/Decorator/Webservice.php
+++ b/Structural/Decorator/Webservice.php
@@ -2,25 +2,19 @@
 
 namespace DesignPatterns\Structural\Decorator;
 
-class Webservice implements RendererInterface
+class Webservice implements RenderableInterface
 {
     /**
-     * @var mixed
+     * @var string
      */
-    protected $data;
+    private $data;
 
-    /**
-     * @param mixed $data
-     */
-    public function __construct($data)
+    public function __construct(string $data)
     {
         $this->data = $data;
     }
 
-    /**
-     * @return string
-     */
-    public function renderData()
+    public function renderData(): string
     {
         return $this->data;
     }
diff --git a/Structural/Decorator/XmlRenderer.php b/Structural/Decorator/XmlRenderer.php
new file mode 100644
index 0000000..012da47
--- /dev/null
+++ b/Structural/Decorator/XmlRenderer.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace DesignPatterns\Structural\Decorator;
+
+class XmlRenderer extends RendererDecorator
+{
+    public function renderData(): string
+    {
+        $doc = new \DOMDocument();
+        $data = $this->wrapped->renderData();
+        $doc->appendChild($doc->createElement('content', $data));
+
+        return $doc->saveXML();
+    }
+}