diff --git a/src/Symfony/Component/Translation/LoggingTranslator.php b/src/Symfony/Component/Translation/LoggingTranslator.php
index d6b711d27e817..3a84bf117050c 100644
--- a/src/Symfony/Component/Translation/LoggingTranslator.php
+++ b/src/Symfony/Component/Translation/LoggingTranslator.php
@@ -82,7 +82,9 @@ public function transChoice($id, $number, array $parameters = [], $domain = null
      */
     public function setLocale($locale)
     {
+        $prev = $this->translator->getLocale();
         $this->translator->setLocale($locale);
+        $this->logger->debug(sprintf('The locale of the translator has changed from "%s" to "%s".', $prev, $locale));
     }
 
     /**