diff --git a/src/Composer/Autoload/AutoloadGenerator.php b/src/Composer/Autoload/AutoloadGenerator.php
index 99263c0bf..47e75a944 100644
--- a/src/Composer/Autoload/AutoloadGenerator.php
+++ b/src/Composer/Autoload/AutoloadGenerator.php
@@ -31,7 +31,7 @@ class AutoloadGenerator
 <?php
 
 // autoload.php generated by Composer
-if (!class_exists('Composer\\Autoload\\ClassLoader')) {
+if (!class_exists('Composer\\Autoload\\ClassLoader', false)) {
     require __DIR__.'/ClassLoader.php';
 }
 
@@ -120,7 +120,6 @@ EOF;
 
         file_put_contents($targetDir.'/autoload.php', $autoloadFile);
         file_put_contents($targetDir.'/autoload_namespaces.php', $namespacesFile);
-        file_put_contents($targetDir.'/autoload_namespaces.php', $namespacesFile);
         copy(__DIR__.'/ClassLoader.php', $targetDir.'/ClassLoader.php');
     }