diff --git a/src/Symfony/Component/VarDumper/Tests/Dumper/CliDumperTest.php b/src/Symfony/Component/VarDumper/Tests/Dumper/CliDumperTest.php
index ae81eb33f2..43fb664a11 100644
--- a/src/Symfony/Component/VarDumper/Tests/Dumper/CliDumperTest.php
+++ b/src/Symfony/Component/VarDumper/Tests/Dumper/CliDumperTest.php
@@ -348,7 +348,7 @@ EOTXT
      */
     public function testThrowingCaster()
     {
-        $out = fopen('php://memory', 'r+b');
+        $out = fopen('php://memory', 'r+');
 
         require_once __DIR__.'/../Fixtures/Twig.php';
         $twig = new \__TwigTemplate_VarDumperFixture_u75a09(new Environment(new FilesystemLoader()));