diff --git a/src/Symfony/Component/HttpKernel/Fragment/InlineFragmentRenderer.php b/src/Symfony/Component/HttpKernel/Fragment/InlineFragmentRenderer.php
index 2c8d58f956..25007bd115 100644
--- a/src/Symfony/Component/HttpKernel/Fragment/InlineFragmentRenderer.php
+++ b/src/Symfony/Component/HttpKernel/Fragment/InlineFragmentRenderer.php
@@ -111,10 +111,11 @@ class InlineFragmentRenderer extends RoutableFragmentRenderer
         // Sub-request object will point to localhost as client ip and real client ip
         // will be included into trusted header for client ip
         try {
-            $trustedHeaderName = Request::getTrustedHeaderName(Request::HEADER_CLIENT_IP);
-            $currentXForwardedFor = $request->headers->get($trustedHeaderName, '');
+            if ($trustedHeaderName = Request::getTrustedHeaderName(Request::HEADER_CLIENT_IP)) {
+                $currentXForwardedFor = $request->headers->get($trustedHeaderName, '');
 
-            $server['HTTP_'.$trustedHeaderName] = ($currentXForwardedFor ? $currentXForwardedFor.', ' : '').$request->getClientIp();
+                $server['HTTP_'.$trustedHeaderName] = ($currentXForwardedFor ? $currentXForwardedFor.', ' : '').$request->getClientIp();
+            }
         } catch (\InvalidArgumentException $e) {
             // Do nothing
         }
diff --git a/src/Symfony/Component/HttpKernel/Tests/Fragment/InlineFragmentRendererTest.php b/src/Symfony/Component/HttpKernel/Tests/Fragment/InlineFragmentRendererTest.php
index f405dae09c..ded1071f9f 100644
--- a/src/Symfony/Component/HttpKernel/Tests/Fragment/InlineFragmentRendererTest.php
+++ b/src/Symfony/Component/HttpKernel/Tests/Fragment/InlineFragmentRendererTest.php
@@ -67,6 +67,26 @@ class InlineFragmentRendererTest extends \PHPUnit_Framework_TestCase
         $strategy->render(new ControllerReference('main_controller', array('object' => $object), array()), Request::create('/'));
     }
 
+    public function testRenderWithTrustedHeaderDisabled()
+    {
+        $trustedHeaderName = Request::getTrustedHeaderName(Request::HEADER_CLIENT_IP);
+
+        Request::setTrustedHeaderName(Request::HEADER_CLIENT_IP, '');
+
+        $kernel = $this->getMock('Symfony\Component\HttpKernel\HttpKernelInterface');
+        $kernel
+            ->expects($this->any())
+            ->method('handle')
+            ->with(Request::create('/'))
+        ;
+
+        $strategy = new InlineFragmentRenderer($kernel);
+
+        $strategy->render('/', Request::create('/'));
+        
+        Request::setTrustedHeaderName(Request::HEADER_CLIENT_IP, $trustedHeaderName);
+    }
+
     /**
      * @expectedException \RuntimeException
      */
@@ -147,8 +167,11 @@ class InlineFragmentRendererTest extends \PHPUnit_Framework_TestCase
     {
         $expectedSubRequest = Request::create('/');
         $expectedSubRequest->headers->set('Surrogate-Capability', 'abc="ESI/1.0"');
-        $expectedSubRequest->headers->set('x-forwarded-for', array('127.0.0.1'));
-        $expectedSubRequest->server->set('HTTP_X_FORWARDED_FOR', '127.0.0.1');
+
+        if (Request::getTrustedHeaderName(Request::HEADER_CLIENT_IP)) {
+            $expectedSubRequest->headers->set('x-forwarded-for', array('127.0.0.1'));
+            $expectedSubRequest->server->set('HTTP_X_FORWARDED_FOR', '127.0.0.1');
+        }
 
         $kernel = $this->getMock('Symfony\Component\HttpKernel\HttpKernelInterface');
         $kernel
@@ -163,4 +186,14 @@ class InlineFragmentRendererTest extends \PHPUnit_Framework_TestCase
         $request->headers->set('Surrogate-Capability', 'abc="ESI/1.0"');
         $strategy->render('/', $request);
     }
+
+    public function testESIHeaderIsKeptInSubrequestWithTrustedHeaderDisabled()
+    {
+        $trustedHeaderName = Request::getTrustedHeaderName(Request::HEADER_CLIENT_IP);
+        Request::setTrustedHeaderName(Request::HEADER_CLIENT_IP, '');
+
+        $this->testESIHeaderIsKeptInSubrequest();
+
+        Request::setTrustedHeaderName(Request::HEADER_CLIENT_IP, $trustedHeaderName);
+    }
 }