diff --git a/src/Composer/Installer.php b/src/Composer/Installer.php
index 5fcc6efa2..c5c0f7a21 100644
--- a/src/Composer/Installer.php
+++ b/src/Composer/Installer.php
@@ -200,7 +200,7 @@ class Installer
         }
 
         if ($this->runScripts) {
-            $_SERVER['COMPOSER_DEV_MODE'] = (int) $this->devMode;
+            $_SERVER['COMPOSER_DEV_MODE'] = $this->devMode ? '1' : '0';
             putenv('COMPOSER_DEV_MODE='.$_SERVER['COMPOSER_DEV_MODE']);
 
             // dispatch pre event