diff --git a/src/Composer/Command/DumpAutoloadCommand.php b/src/Composer/Command/DumpAutoloadCommand.php
index 86d351505..b30fbd140 100644
--- a/src/Composer/Command/DumpAutoloadCommand.php
+++ b/src/Composer/Command/DumpAutoloadCommand.php
@@ -30,7 +30,7 @@ class DumpAutoloadCommand extends Command
             ->setAliases(array('dumpautoload'))
             ->setDescription('Dumps the autoloader')
             ->setDefinition(array(
-                new InputOption('optimize', 'o', InputOption::VALUE_NONE, 'Optimizes PSR0 packages to be loaded with classmaps too, good for production.'),
+                new InputOption('optimize', 'o', InputOption::VALUE_NONE, 'Optimizes PSR0 and PSR4 packages to be loaded with classmaps too, good for production.'),
                 new InputOption('no-dev', null, InputOption::VALUE_NONE, 'Disables autoload-dev rules.'),
             ))
             ->setHelp(<<<EOT