diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/TranslationUpdateCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/TranslationUpdateCommand.php
index 65b8013450..ed871a5410 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/TranslationUpdateCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/TranslationUpdateCommand.php
@@ -83,7 +83,7 @@ class TranslationUpdateCommand extends Command
                 new InputOption('clean', null, InputOption::VALUE_NONE, 'Should clean not found messages'),
                 new InputOption('domain', null, InputOption::VALUE_OPTIONAL, 'Specify the domain to update'),
                 new InputOption('xliff-version', null, InputOption::VALUE_OPTIONAL, 'Override the default xliff version', '1.2'),
-                new InputOption('sort', null, InputOption::VALUE_OPTIONAL, 'Return list of messages sorted alphabetically'),
+                new InputOption('sort', null, InputOption::VALUE_OPTIONAL, 'Return list of messages sorted alphabetically', 'asc'),
             ])
             ->setDescription('Updates the translation file')
             ->setHelp(<<<'EOF'
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Command/TranslationUpdateCommandTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Command/TranslationUpdateCommandTest.php
index 856ba6408e..2e33e2cc3f 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Command/TranslationUpdateCommandTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Command/TranslationUpdateCommandTest.php
@@ -48,6 +48,14 @@ class TranslationUpdateCommandTest extends TestCase
         $this->assertRegExp('/3 messages were successfully extracted/', $tester->getDisplay());
     }
 
+    public function testDumpSortWithoutValueAndClean()
+    {
+        $tester = $this->createCommandTester(['messages' => ['foo' => 'foo', 'test' => 'test', 'bar' => 'bar']]);
+        $tester->execute(['command' => 'translation:update', 'locale' => 'en', 'bundle' => 'foo', '--dump-messages' => true, '--clean' => true, '--sort']);
+        $this->assertRegExp("/\*bar\*foo\*test/", preg_replace('/\s+/', '', $tester->getDisplay()));
+        $this->assertRegExp('/3 messages were successfully extracted/', $tester->getDisplay());
+    }
+
     public function testDumpWrongSortAndClean()
     {
         $tester = $this->createCommandTester(['messages' => ['foo' => 'foo', 'test' => 'test', 'bar' => 'bar']]);