diff --git a/Path.php b/Path.php
index 6ccb2e99a..0bbd5b477 100644
--- a/Path.php
+++ b/Path.php
@@ -257,7 +257,7 @@ public static function getRoot(string $path): string
      * @param string|null $extension if specified, only that extension is cut
      *                               off (may contain leading dot)
      */
-    public static function getFilenameWithoutExtension(string $path, string $extension = null)
+    public static function getFilenameWithoutExtension(string $path, string $extension = null): string
     {
         if ('' === $path) {
             return '';