diff --git a/src/Symfony/Component/Process/Tests/ErrorProcessInitiator.php b/src/Symfony/Component/Process/Tests/ErrorProcessInitiator.php
index 271f6d1acc13c..c37aeb5c8ffd9 100755
--- a/src/Symfony/Component/Process/Tests/ErrorProcessInitiator.php
+++ b/src/Symfony/Component/Process/Tests/ErrorProcessInitiator.php
@@ -14,7 +14,7 @@
 use Symfony\Component\Process\Exception\ProcessTimedOutException;
 use Symfony\Component\Process\Process;
 
-require dirname(__DIR__).'/vendor/autoload.php';
+require \dirname(__DIR__).'/vendor/autoload.php';
 
 list('e' => $php) = getopt('e:') + ['e' => 'php'];