diff --git a/src/CosAdapter.php b/src/CosAdapter.php
index b460df0..d4da6c6 100644
--- a/src/CosAdapter.php
+++ b/src/CosAdapter.php
@@ -449,6 +449,10 @@ protected function listObjects(string $directory = '', bool $recursive = false)
 
     protected function normalizeVisibility(string $visibility): string
     {
-        return $visibility === Visibility::PUBLIC ? 'public-read' : 'default';
+        return match ($visibility) {
+            Visibility::PUBLIC => 'public-read',
+            Visibility::PRIVATE => 'private',
+            default => 'default',
+        };
     }
 }