diff --git a/src/Composer/EventDispatcher/EventDispatcher.php b/src/Composer/EventDispatcher/EventDispatcher.php
index 7cc91b7cc..65ee752dd 100644
--- a/src/Composer/EventDispatcher/EventDispatcher.php
+++ b/src/Composer/EventDispatcher/EventDispatcher.php
@@ -145,13 +145,18 @@ class EventDispatcher
      */
     protected function doDispatch(Event $event)
     {
+        $pathStr = 'PATH';
+        if (!isset($_SERVER[$pathStr])) {
+            $pathStr = 'Path';
+        }
+        
         // add the bin dir to the PATH to make local binaries of deps usable in scripts
         $binDir = $this->composer->getConfig()->get('bin-dir');
         if (is_dir($binDir)) {
             $binDir = realpath($binDir);
-            if (isset($_SERVER['PATH']) && !preg_match('{(^|'.PATH_SEPARATOR.')'.preg_quote($binDir).'($|'.PATH_SEPARATOR.')}', $_SERVER['PATH'])) {
-                $_SERVER['PATH'] = $binDir.PATH_SEPARATOR.getenv('PATH');
-                putenv('PATH='.$_SERVER['PATH']);
+            if (isset($_SERVER[$pathStr]) && !preg_match('{(^|'.PATH_SEPARATOR.')'.preg_quote($binDir).'($|'.PATH_SEPARATOR.')}', $_SERVER[$pathStr])) {
+                $_SERVER[$pathStr] = $binDir.PATH_SEPARATOR.getenv($pathStr);
+                putenv($pathStr.'='.$_SERVER[$pathStr]);
             }
         }