diff --git a/src/Symfony/Component/HttpFoundation/JsonResponse.php b/src/Symfony/Component/HttpFoundation/JsonResponse.php
index 31747ce81416b..e49c6b276216f 100644
--- a/src/Symfony/Component/HttpFoundation/JsonResponse.php
+++ b/src/Symfony/Component/HttpFoundation/JsonResponse.php
@@ -34,14 +34,12 @@ class JsonResponse extends Response
     protected $encodingOptions = self::DEFAULT_ENCODING_OPTIONS;
 
     /**
-     * Constructor.
-     *
-     * @param mixed $data       The response data
-     * @param int   $status     The response status code
-     * @param array $headers    An array of response headers
-     * @param bool  $preEncoded If the data is already a JSON string
+     * @param mixed $data    The response data
+     * @param int   $status  The response status code
+     * @param array $headers An array of response headers
+     * @param bool  $json    If the data is already a JSON string
      */
-    public function __construct($data = null, $status = 200, $headers = array(), $preEncoded = false)
+    public function __construct($data = null, $status = 200, $headers = array(), $json = false)
     {
         parent::__construct('', $status, $headers);
 
@@ -49,7 +47,7 @@ public function __construct($data = null, $status = 200, $headers = array(), $pr
             $data = new \ArrayObject();
         }
 
-        $this->setData($data, $preEncoded);
+        $json ? $this->setJson($data) : $this->setData($data);
     }
 
     /**
@@ -87,46 +85,57 @@ public function setCallback($callback = null)
         return $this->update();
     }
 
+    /**
+     * Sets a raw string containing a JSON document to be sent.
+     *
+     * @param string $data
+     *
+     * @return JsonResponse
+     *
+     * @throws \InvalidArgumentException
+     */
+    public function setJson($json)
+    {
+        $this->data = $json;
+
+        return $this->update();
+    }
+
     /**
      * Sets the data to be sent as JSON.
      *
      * @param mixed $data
-     * @param bool  $preEncoded If the data is already a JSON string
      *
      * @return JsonResponse
      *
      * @throws \InvalidArgumentException
      */
-    public function setData($data = array(), $preEncoded = false)
+    public function setData($data = array())
     {
-        if (!$preEncoded) {
-            if (defined('HHVM_VERSION')) {
-                // HHVM does not trigger any warnings and let exceptions
-                // thrown from a JsonSerializable object pass through.
-                // If only PHP did the same...
+        if (defined('HHVM_VERSION')) {
+            // HHVM does not trigger any warnings and let exceptions
+            // thrown from a JsonSerializable object pass through.
+            // If only PHP did the same...
+            $data = json_encode($data, $this->encodingOptions);
+        } else {
+            try {
+                // PHP 5.4 and up wrap exceptions thrown by JsonSerializable
+                // objects in a new exception that needs to be removed.
+                // Fortunately, PHP 5.5 and up do not trigger any warning anymore.
                 $data = json_encode($data, $this->encodingOptions);
-            } else {
-                try {
-                    // PHP 5.4 and up wrap exceptions thrown by JsonSerializable
-                    // objects in a new exception that needs to be removed.
-                    // Fortunately, PHP 5.5 and up do not trigger any warning anymore.
-                    $data = json_encode($data, $this->encodingOptions);
-                } catch (\Exception $e) {
-                    if ('Exception' === get_class($e) && 0 === strpos($e->getMessage(), 'Failed calling ')) {
-                        throw $e->getPrevious() ?: $e;
-                    }
-                    throw $e;
+            } catch (\Exception $e) {
+                if ('Exception' === get_class($e) && 0 === strpos($e->getMessage(), 'Failed calling ')) {
+                    throw $e->getPrevious() ?: $e;
                 }
-            }
-
-            if (JSON_ERROR_NONE !== json_last_error()) {
-                throw new \InvalidArgumentException(json_last_error_msg());
+                throw $e;
             }
         }
 
-        $this->data = $data;
+        if (JSON_ERROR_NONE !== json_last_error()) {
+            throw new \InvalidArgumentException(json_last_error_msg());
+        }
 
-        return $this->update();
+        return $this->setJson($data);
     }
 
     /**
diff --git a/src/Symfony/Component/HttpFoundation/Tests/JsonResponseTest.php b/src/Symfony/Component/HttpFoundation/Tests/JsonResponseTest.php
index eac2f60fe7f8b..1dd2e60c062dd 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/JsonResponseTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/JsonResponseTest.php
@@ -75,7 +75,7 @@ public function testConstructorWithCustomContentType()
         $this->assertSame('application/vnd.acme.blog-v1+json', $response->headers->get('Content-Type'));
     }
 
-    public function testConstructorWithPreEncoded()
+    public function testSetJson()
     {
         $response = new JsonResponse('1', 200, array(), true);
         $this->assertEquals('1', $response->getContent());
@@ -83,7 +83,8 @@ public function testConstructorWithPreEncoded()
         $response = new JsonResponse('[1]', 200, array(), true);
         $this->assertEquals('[1]', $response->getContent());
 
-        $response = new JsonResponse('true', 200, array(), true);
+        $response = new JsonResponse(null, 200, array());
+        $response->setJson('true');
         $this->assertEquals('true', $response->getContent());
     }