diff --git a/src/Symfony/Component/Translation/Extractor/ExtractorInterface.php b/src/Symfony/Component/Translation/Extractor/ExtractorInterface.php
index 1adc757003..34e6b2d6ef 100644
--- a/src/Symfony/Component/Translation/Extractor/ExtractorInterface.php
+++ b/src/Symfony/Component/Translation/Extractor/ExtractorInterface.php
@@ -24,7 +24,7 @@ interface ExtractorInterface
     /**
      * Extracts translation messages from files, a file or a directory to the catalogue.
      *
-     * @param string|iterable $resource Files, a file or a directory
+     * @param string|iterable<string> $resource Files, a file or a directory
      */
     public function extract($resource, MessageCatalogue $catalogue);