diff --git a/src/Symfony/Component/Translation/Translator.php b/src/Symfony/Component/Translation/Translator.php
index 8e3cda857c0d..d13adc07c6e0 100644
--- a/src/Symfony/Component/Translation/Translator.php
+++ b/src/Symfony/Component/Translation/Translator.php
@@ -308,7 +308,7 @@ protected function computeFallbackLocales($locale)
      */
     private function assertValidLocale($locale)
     {
-        if (0 !== preg_match('/[^a-z0-9@_\\.\\-]+/i', $locale, $match)) {
+        if (1 !== preg_match('/^[a-z0-9@_\\.\\-]*$/i', $locale)) {
             throw new \InvalidArgumentException(sprintf('Invalid locale: %s.', $locale));
         }
     }