diff --git a/src/Illuminate/Foundation/PackageManifest.php b/src/Illuminate/Foundation/PackageManifest.php
index 202a8beb271d..9767feb99f22 100644
--- a/src/Illuminate/Foundation/PackageManifest.php
+++ b/src/Illuminate/Foundation/PackageManifest.php
@@ -4,6 +4,7 @@
 
 use Exception;
 use Illuminate\Filesystem\Filesystem;
+use Illuminate\Support\Env;
 
 class PackageManifest
 {
@@ -55,7 +56,7 @@ public function __construct(Filesystem $files, $basePath, $manifestPath)
         $this->files = $files;
         $this->basePath = $basePath;
         $this->manifestPath = $manifestPath;
-        $this->vendorPath = $basePath.'/vendor';
+        $this->vendorPath = Env::get('COMPOSER_VENDOR_DIR') ?: $basePath.'/vendor';
     }
 
     /**