diff --git a/src/Composer/Factory.php b/src/Composer/Factory.php
index d14cee7bd..8a2a6a815 100644
--- a/src/Composer/Factory.php
+++ b/src/Composer/Factory.php
@@ -507,6 +507,7 @@ class Factory
             'minimum-stability',
             'prefer-stable',
             'repositories',
+            'extra',
         );
 
         $relevantContent = array();