diff --git a/src/Symfony/Component/Console/Output/ConsoleOutput.php b/src/Symfony/Component/Console/Output/ConsoleOutput.php
index d71f062dfb62b..8e1f360141497 100644
--- a/src/Symfony/Component/Console/Output/ConsoleOutput.php
+++ b/src/Symfony/Component/Console/Output/ConsoleOutput.php
@@ -125,7 +125,13 @@ protected function hasStderrSupport()
      */
     private function isRunningOS400()
     {
-        return 'OS400' === PHP_OS;
+        $checks = array(
+            function_exists('php_uname') ? php_uname('s') : '',
+            getenv('OSTYPE'),
+            PHP_OS,
+        );
+
+        return false !== stristr(implode(';', $checks), 'OS400');
     }
 
     /**