diff --git a/src/Composer/Console/Application.php b/src/Composer/Console/Application.php
index e92b45863..762425272 100644
--- a/src/Composer/Console/Application.php
+++ b/src/Composer/Console/Application.php
@@ -129,7 +129,7 @@ class Application extends BaseApplication
     {
         $this->disablePluginsByDefault = $input->hasParameterOption('--no-plugins');
 
-        if (getenv('COMPOSER_NO_INTERACTION') || !Platform::isTty(STDIN)) {
+        if (getenv('COMPOSER_NO_INTERACTION') || !Platform::isTty(defined('STDIN') ? STDIN : fopen('php://stdin', 'r'))) {
             $input->setInteractive(false);
         }
 
diff --git a/src/Composer/Util/Platform.php b/src/Composer/Util/Platform.php
index a582a6fad..72396f0a7 100644
--- a/src/Composer/Util/Platform.php
+++ b/src/Composer/Util/Platform.php
@@ -93,7 +93,7 @@ class Platform
     public static function isTty($fd = null)
     {
         if ($fd === null) {
-            $fd = STDOUT;
+            $fd = defined('STDOUT') ? STDOUT : fopen('php://stdout', 'w');
         }
 
         // modern cross-platform function, includes the fstat