diff --git a/FileinfoMimeTypeGuesser.php b/FileinfoMimeTypeGuesser.php
index 5e96b24..aff5901 100644
--- a/FileinfoMimeTypeGuesser.php
+++ b/FileinfoMimeTypeGuesser.php
@@ -24,7 +24,7 @@ class FileinfoMimeTypeGuesser implements MimeTypeGuesserInterface
     private ?string $magicFile;
 
     /**
-     * @param string $magicFile A magic file to use with the finfo instance
+     * @param string|null $magicFile A magic file to use with the finfo instance
      *
      * @see http://www.php.net/manual/en/function.finfo-open.php
      */