diff --git a/src/Symfony/Component/HttpKernel/Kernel.php b/src/Symfony/Component/HttpKernel/Kernel.php
index 8d4953886e3a0..b5df6c6cdb24d 100644
--- a/src/Symfony/Component/HttpKernel/Kernel.php
+++ b/src/Symfony/Component/HttpKernel/Kernel.php
@@ -82,7 +82,6 @@ public function __construct($environment, $debug)
         $this->environment = $environment;
         $this->debug = (bool) $debug;
         $this->rootDir = $this->getRootDir();
-        $this->projectDir = $this->getProjectDir();
         $this->name = $this->getName();
 
         if ($this->debug) {
@@ -604,7 +603,7 @@ protected function getKernelParameters()
         return array_merge(
             array(
                 'kernel.root_dir' => realpath($this->rootDir) ?: $this->rootDir,
-                'kernel.project_dir' => realpath($this->projectDir) ?: $this->projectDir,
+                'kernel.project_dir' => realpath($this->getProjectDir()) ?: $this->getProjectDir(),
                 'kernel.environment' => $this->environment,
                 'kernel.debug' => $this->debug,
                 'kernel.name' => $this->name,
diff --git a/src/Symfony/Component/HttpKernel/Tests/KernelTest.php b/src/Symfony/Component/HttpKernel/Tests/KernelTest.php
index 4cc31d49903b1..d2a27d03aaf37 100644
--- a/src/Symfony/Component/HttpKernel/Tests/KernelTest.php
+++ b/src/Symfony/Component/HttpKernel/Tests/KernelTest.php
@@ -12,6 +12,7 @@
 namespace Symfony\Component\HttpKernel\Tests;
 
 use PHPUnit\Framework\TestCase;
+use Symfony\Component\Config\Loader\LoaderInterface;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\HttpKernel\Bundle\BundleInterface;
 use Symfony\Component\HttpKernel\Config\EnvParametersResource;
@@ -761,6 +762,15 @@ public function testSymfonyEnvironmentVariables()
         unset($_SERVER['SYMFONY__FOO__BAR']);
     }
 
+    public function testProjectDirExtension()
+    {
+        $kernel = new CustomProjectDirKernel('test', true);
+        $kernel->boot();
+
+        $this->assertSame('foo', $kernel->getProjectDir());
+        $this->assertSame('foo', $kernel->getContainer()->getParameter('kernel.project_dir'));
+    }
+
     /**
      * Returns a mock for the BundleInterface.
      *
@@ -857,3 +867,34 @@ public function handle(Request $request, $type = self::MASTER_REQUEST, $catch =
     {
     }
 }
+
+class CustomProjectDirKernel extends Kernel
+{
+    private $baseDir;
+
+    public function __construct()
+    {
+        parent::__construct('test', false);
+
+        $this->baseDir = 'foo';
+    }
+
+    public function registerBundles()
+    {
+        return array();
+    }
+
+    public function registerContainerConfiguration(LoaderInterface $loader)
+    {
+    }
+
+    public function getProjectDir()
+    {
+        return $this->baseDir;
+    }
+
+    public function getRootDir()
+    {
+        return __DIR__.'/Fixtures';
+    }
+}