diff --git a/src/Composer/Repository/ArtifactRepository.php b/src/Composer/Repository/ArtifactRepository.php
index 50a08241f..a8002123a 100644
--- a/src/Composer/Repository/ArtifactRepository.php
+++ b/src/Composer/Repository/ArtifactRepository.php
@@ -27,6 +27,7 @@ class ArtifactRepository extends ArrayRepository implements ConfigurableReposito
 
     protected $lookup;
     protected $repoConfig;
+    private $io;
 
     public function __construct(array $repoConfig, IOInterface $io)
     {