diff --git a/CHANGELOG.md b/CHANGELOG.md
index 568c5b7..9ca335a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,7 +6,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
-* Nothing
+### Changed
+
+* Change signature of `RepositoryInterface::save()`. It should now receive an `ItemInterface` instead of a `ItemDocumentInterface`.
 
 ## [0.19.0] - 2019-07-10
 
diff --git a/README.MD b/README.MD
index 13df901..23d7119 100644
--- a/README.MD
+++ b/README.MD
@@ -253,13 +253,6 @@ $repository->all(['include' => 'author', 'page' => ['limit' => 15, 'offset' => 0
 ```
 
 
-## DocumentFactory
-
-The `Repository` and `DocumentClient` both require `ItemDocumentInterface` instances when creating or updating resources.
-Such documents can easily be created using the `DocumentFactory` by giving it a `DataInterface` instance.
-This can be an `ItemInterface`, usually created by the [ItemHydrator](#itemhydrator), or a `Collection`.
-
-
 ## ItemHydrator
 
 The `ItemHydrator` can be used to fill/hydrate an item and its relations using an associative array with attributes.
@@ -267,15 +260,15 @@ This is useful if you would like to hydrate an item with POST data from your req
 
 ``` php
 $typeMapper = app(Swis\JsonApi\Client\TypeMapper::class);
-$itemDocumentBuilder = app(Swis\JsonApi\Client\ItemDocumentBuilder::class);
+$itemHydrator = app(Swis\JsonApi\Client\ItemHydrator::class);
 $blogRepository = app(App\Repositiories\BlogRepository::class);
 
-$itemDocument = $itemDocumentBuilder->build(
+$item = $itemHydrator->hydrate(
     $typeMapper->getMapping('blog'),
     request()->all(['title', 'author', 'date', 'content', 'tags']),
     request()->id
 );
-$blogRepository->save($itemDocument);
+$blogRepository->save($item);
 ```
 
 ### Relations
@@ -300,7 +293,7 @@ $attributes = [
         56,
     ],
 ];
-$itemDocument = $itemDocumentBuilder->build($typeMapper->getMapping('blog'), $attributes);
+$itemDocument = $itemHydrator->hydrate($typeMapper->getMapping('blog'), $attributes);
 
 echo json_encode($itemDocument, JSON_PRETTY_PRINT);
 
@@ -376,6 +369,13 @@ It can take everything your request factory takes as input data and returns the
 It does not parse or validate the response or hydrate items!
 
 
+## DocumentFactory
+
+The `DocumentClient` requires `ItemDocumentInterface` instances when creating or updating resources.
+Such documents can easily be created using the `DocumentFactory` by giving it a `DataInterface` instance.
+This can be an `ItemInterface`, usually created by the [ItemHydrator](#itemhydrator), or a `Collection`.
+
+
 ## Service Provider
 
 The `\Swis\JsonApi\Client\Providers\ServiceProvider` registers the `TypeMapper`, `JsonApi\Parser` and both clients; `Client` and `DocumentClient`.
diff --git a/src/Interfaces/RepositoryInterface.php b/src/Interfaces/RepositoryInterface.php
index ee592b2..5d8ffdf 100644
--- a/src/Interfaces/RepositoryInterface.php
+++ b/src/Interfaces/RepositoryInterface.php
@@ -17,11 +17,11 @@ public function all();
     public function find(string $id);
 
     /**
-     * @param \Swis\JsonApi\Client\Interfaces\ItemDocumentInterface $document
+     * @param \Swis\JsonApi\Client\Interfaces\ItemInterface $item
      *
      * @return \Swis\JsonApi\Client\Interfaces\ItemDocumentInterface
      */
-    public function save(ItemDocumentInterface $document);
+    public function save(ItemInterface $item);
 
     /**
      * @param string $id
diff --git a/src/Repository.php b/src/Repository.php
index 38f43a7..573dd67 100644
--- a/src/Repository.php
+++ b/src/Repository.php
@@ -3,7 +3,7 @@
 namespace Swis\JsonApi\Client;
 
 use Swis\JsonApi\Client\Interfaces\DocumentClientInterface;
-use Swis\JsonApi\Client\Interfaces\ItemDocumentInterface;
+use Swis\JsonApi\Client\Interfaces\ItemInterface;
 use Swis\JsonApi\Client\Interfaces\RepositoryInterface;
 
 class Repository implements RepositoryInterface
@@ -13,6 +13,11 @@ class Repository implements RepositoryInterface
      */
     protected $client;
 
+    /**
+     * @var \Swis\JsonApi\Client\DocumentFactory
+     */
+    protected $documentFactory;
+
     /**
      * @var string
      */
@@ -20,10 +25,12 @@ class Repository implements RepositoryInterface
 
     /**
      * @param \Swis\JsonApi\Client\Interfaces\DocumentClientInterface $client
+     * @param \Swis\JsonApi\Client\DocumentFactory                    $documentFactory
      */
-    public function __construct(DocumentClientInterface $client)
+    public function __construct(DocumentClientInterface $client, DocumentFactory $documentFactory)
     {
         $this->client = $client;
+        $this->documentFactory = $documentFactory;
     }
 
     /**
@@ -74,42 +81,45 @@ public function find(string $id, array $parameters = [])
     }
 
     /**
-     * @param \Swis\JsonApi\Client\Interfaces\ItemDocumentInterface $document
-     * @param array                                                 $parameters
+     * @param \Swis\JsonApi\Client\Interfaces\ItemInterface $item
+     * @param array                                         $parameters
      *
      * @return \Swis\JsonApi\Client\Interfaces\DocumentInterface
      */
-    public function save(ItemDocumentInterface $document, array $parameters = [])
+    public function save(ItemInterface $item, array $parameters = [])
     {
-        if ($document->getData()->isNew()) {
-            return $this->saveNew($document, $parameters);
+        if ($item->isNew()) {
+            return $this->saveNew($item, $parameters);
         }
 
-        return $this->saveExisting($document, $parameters);
+        return $this->saveExisting($item, $parameters);
     }
 
     /**
-     * @param \Swis\JsonApi\Client\Interfaces\ItemDocumentInterface $document
-     * @param array                                                 $parameters
+     * @param \Swis\JsonApi\Client\Interfaces\ItemInterface $item
+     * @param array                                         $parameters
      *
      * @return \Swis\JsonApi\Client\Interfaces\DocumentInterface
      */
-    protected function saveNew(ItemDocumentInterface $document, array $parameters = [])
+    protected function saveNew(ItemInterface $item, array $parameters = [])
     {
-        return $this->getClient()->post($this->getEndpoint().'?'.http_build_query($parameters), $document);
+        return $this->getClient()->post(
+            $this->getEndpoint().'?'.http_build_query($parameters),
+            $this->documentFactory->make($item)
+        );
     }
 
     /**
-     * @param \Swis\JsonApi\Client\Interfaces\ItemDocumentInterface $document
-     * @param array                                                 $parameters
+     * @param \Swis\JsonApi\Client\Interfaces\ItemInterface $item
+     * @param array                                         $parameters
      *
      * @return \Swis\JsonApi\Client\Interfaces\DocumentInterface
      */
-    protected function saveExisting(ItemDocumentInterface $document, array $parameters = [])
+    protected function saveExisting(ItemInterface $item, array $parameters = [])
     {
         return $this->getClient()->patch(
-            $this->getEndpoint().'/'.urlencode($document->getData()->getId()).'?'.http_build_query($parameters),
-            $document
+            $this->getEndpoint().'/'.urlencode($item->getId()).'?'.http_build_query($parameters),
+            $this->documentFactory->make($item)
         );
     }
 
diff --git a/tests/RepositoryTest.php b/tests/RepositoryTest.php
index 63ceef9..6f8e649 100644
--- a/tests/RepositoryTest.php
+++ b/tests/RepositoryTest.php
@@ -4,6 +4,7 @@
 
 use PHPUnit\Framework\TestCase;
 use Swis\JsonApi\Client\Document;
+use Swis\JsonApi\Client\DocumentFactory;
 use Swis\JsonApi\Client\Interfaces\DocumentClientInterface;
 use Swis\JsonApi\Client\Item;
 use Swis\JsonApi\Client\ItemDocument;
@@ -18,7 +19,7 @@ public function it_can_get_the_client()
     {
         /** @var \PHPUnit\Framework\MockObject\MockObject|\Swis\JsonApi\Client\Interfaces\DocumentClientInterface $client */
         $client = $this->getMockBuilder(DocumentClientInterface::class)->getMock();
-        $repository = new MockRepository($client);
+        $repository = new MockRepository($client, new DocumentFactory());
 
         $this->assertSame($client, $repository->getClient());
     }
@@ -30,7 +31,7 @@ public function it_can_get_the_endpoint()
     {
         /** @var \PHPUnit\Framework\MockObject\MockObject|\Swis\JsonApi\Client\Interfaces\DocumentClientInterface $client */
         $client = $this->getMockBuilder(DocumentClientInterface::class)->getMock();
-        $repository = new MockRepository($client);
+        $repository = new MockRepository($client, new DocumentFactory());
 
         $this->assertSame('mocks', $repository->getEndpoint());
     }
@@ -50,7 +51,7 @@ public function it_can_get_all()
             ->with('mocks?foo=bar')
             ->willReturn($document);
 
-        $repository = new MockRepository($client);
+        $repository = new MockRepository($client, new DocumentFactory());
 
         $this->assertSame($document, $repository->all(['foo' => 'bar']));
     }
@@ -70,7 +71,7 @@ public function it_can_take_one()
             ->with('mocks?foo=bar')
             ->willReturn($document);
 
-        $repository = new MockRepository($client);
+        $repository = new MockRepository($client, new DocumentFactory());
 
         $this->assertSame($document, $repository->take(['foo' => 'bar']));
     }
@@ -90,7 +91,7 @@ public function it_can_find_one()
             ->with('mocks/1?foo=bar')
             ->willReturn($document);
 
-        $repository = new MockRepository($client);
+        $repository = new MockRepository($client, new DocumentFactory());
 
         $this->assertSame($document, $repository->find(1, ['foo' => 'bar']));
     }
@@ -111,9 +112,9 @@ public function it_can_save_new()
             ->with('mocks?foo=bar')
             ->willReturn($document);
 
-        $repository = new MockRepository($client);
+        $repository = new MockRepository($client, new DocumentFactory());
 
-        $this->assertSame($document, $repository->save($document, ['foo' => 'bar']));
+        $this->assertSame($document, $repository->save(new Item(), ['foo' => 'bar']));
     }
 
     /**
@@ -132,9 +133,9 @@ public function it_can_save_existing()
             ->with('mocks/1?foo=bar')
             ->willReturn($document);
 
-        $repository = new MockRepository($client);
+        $repository = new MockRepository($client, new DocumentFactory());
 
-        $this->assertSame($document, $repository->save($document, ['foo' => 'bar']));
+        $this->assertSame($document, $repository->save((new Item())->setId(1), ['foo' => 'bar']));
     }
 
     /**
@@ -152,7 +153,7 @@ public function it_can_delete()
             ->with('mocks/1?foo=bar')
             ->willReturn($document);
 
-        $repository = new MockRepository($client);
+        $repository = new MockRepository($client, new DocumentFactory());
 
         $this->assertSame($document, $repository->delete(1, ['foo' => 'bar']));
     }