diff --git a/core/modules/rest/src/RequestHandler.php b/core/modules/rest/src/RequestHandler.php
index c585166..f5404e6 100644
--- a/core/modules/rest/src/RequestHandler.php
+++ b/core/modules/rest/src/RequestHandler.php
@@ -54,9 +54,15 @@ public function handle(RouteMatchInterface $route_match, Request $request) {
       $method_settings = $config[$plugin][$request->getMethod()];
       if (empty($method_settings['supported_formats']) || in_array($format, $method_settings['supported_formats'])) {
         $definition = $resource->getPluginDefinition();
-        $class = $definition['serialization_class'];
         try {
-          $unserialized = $serializer->deserialize($received, $class, $format, array('request_method' => $method));
+          if (!empty($definition['serialization_class'])) {
+            $unserialized = $serializer->deserialize($received, $definition['serialization_class'], $format, array('request_method' => $method));
+          }
+          // If the plugin does not specify a serialization class just decode
+          // the received data.
+          else {
+            $unserialized = $serializer->decode($received, $format, array('request_method' => $method));
+          }
         }
         catch (UnexpectedValueException $e) {
           $error['error'] = $e->getMessage();
diff --git a/core/modules/rest/src/Tests/ResourceTest.php b/core/modules/rest/src/Tests/ResourceTest.php
index df99cc6..14ff412 100644
--- a/core/modules/rest/src/Tests/ResourceTest.php
+++ b/core/modules/rest/src/Tests/ResourceTest.php
@@ -5,6 +5,7 @@
 use Drupal\Component\Plugin\Exception\PluginNotFoundException;
 use Drupal\Core\Session\AccountInterface;
 use Drupal\user\Entity\Role;
+use Drupal\user\RoleInterface;
 
 /**
  * Tests the structure of a REST resource.
@@ -18,7 +19,7 @@ class ResourceTest extends RESTTestBase {
    *
    * @var array
    */
-  public static $modules = array('hal', 'rest', 'entity_test');
+  public static $modules = array('hal', 'rest', 'entity_test', 'rest_test');
 
   /**
    * The entity.
@@ -104,6 +105,22 @@ public function testAuthentication() {
   }
 
   /**
+   * Tests that serialization_class is optional.
+   */
+  public function testSerializationClassIsOptional() {
+    $this->enableService('serialization_test', 'POST', 'json');
+
+    Role::load(RoleInterface::ANONYMOUS_ID)
+      ->grantPermission('restful post serialization_test')
+      ->save();
+
+    $serialized = $this->container->get('serializer')->serialize(['foo', 'bar'], 'json');
+    $this->httpRequest('serialization_test', 'POST', $serialized, 'application/json');
+    $this->assertResponse(200);
+    $this->assertResponseBody('["foo","bar"]');
+  }
+
+  /**
    * Tests that resource URI paths are formatted properly.
    */
   public function testUriPaths() {
diff --git a/core/modules/rest/tests/modules/rest_test/rest_test.info.yml b/core/modules/rest/tests/modules/rest_test/rest_test.info.yml
index b5f4966..e10b226 100644
--- a/core/modules/rest/tests/modules/rest_test/rest_test.info.yml
+++ b/core/modules/rest/tests/modules/rest_test/rest_test.info.yml
@@ -1,6 +1,6 @@
 name: 'REST test'
 type: module
-description: 'Provides test hooks for REST module.'
+description: 'Provides test hooks and resources for REST module.'
 package: Testing
 version: VERSION
 core: 8.x
diff --git a/core/modules/rest/tests/modules/rest_test/src/Plugin/rest/resource/NoSerializationClassTestResource.php b/core/modules/rest/tests/modules/rest_test/src/Plugin/rest/resource/NoSerializationClassTestResource.php
new file mode 100644
index 0000000..3e83a4c
--- /dev/null
+++ b/core/modules/rest/tests/modules/rest_test/src/Plugin/rest/resource/NoSerializationClassTestResource.php
@@ -0,0 +1,32 @@
+<?php
+
+namespace Drupal\rest_test\Plugin\rest\resource;
+
+use Drupal\rest\Plugin\ResourceBase;
+use Drupal\rest\ResourceResponse;
+
+/**
+ * Class used to test that serialization_class is optional.
+ *
+ * @RestResource(
+ *   id = "serialization_test",
+ *   label = @Translation("Optional serialization_class"),
+ *   serialization_class = "",
+ *   uri_paths = {}
+ * )
+ */
+class NoSerializationClassTestResource extends ResourceBase {
+
+  /**
+   * Responds to a POST request.
+   *
+   * @param array $data
+   *   An array with the payload.
+   *
+   * @return \Drupal\rest\ResourceResponse
+   */
+  public function post(array $data = []) {
+    return new ResourceResponse($data);
+  }
+
+}