diff --git a/src/Composer/IO/BaseIO.php b/src/Composer/IO/BaseIO.php
index 8e8a65eaf..2c67e8a68 100644
--- a/src/Composer/IO/BaseIO.php
+++ b/src/Composer/IO/BaseIO.php
@@ -17,7 +17,7 @@ use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Console\Helper\HelperSet;
 use Composer\Config;
 
-class BaseIO implements IOInterface
+abstract class BaseIO implements IOInterface
 {
     protected $authentications = array();