diff --git a/DownKyi.Core/Storage/StorageCover.cs b/DownKyi.Core/Storage/StorageCover.cs
index dc4e69b..892491d 100644
--- a/DownKyi.Core/Storage/StorageCover.cs
+++ b/DownKyi.Core/Storage/StorageCover.cs
@@ -59,7 +59,7 @@ namespace DownKyi.Core.Storage
                     byte[] bytes = File.ReadAllBytes(cover);
                     Imazen.WebP.Extern.LoadLibrary.LoadWebPOrFail();
                     SimpleDecoder simpleDecoder = new SimpleDecoder();
-                    Bitmap bitmap = simpleDecoder.DecodeFromBytes(bytes, bytes.Length);
+                    Bitmap bitmap = simpleDecoder.DecodeFromBytes(bytes, bytes.LongLength);
 
                     Image thumbnail = bitmap.GetThumbnailImage(width, height, null, IntPtr.Zero);
 
diff --git a/DownKyi.Core/Storage/StorageHeader.cs b/DownKyi.Core/Storage/StorageHeader.cs
index b988269..bc7ec4c 100644
--- a/DownKyi.Core/Storage/StorageHeader.cs
+++ b/DownKyi.Core/Storage/StorageHeader.cs
@@ -59,7 +59,7 @@ namespace DownKyi.Core.Storage
                     byte[] bytes = File.ReadAllBytes(header);
                     Imazen.WebP.Extern.LoadLibrary.LoadWebPOrFail();
                     SimpleDecoder simpleDecoder = new SimpleDecoder();
-                    Bitmap bitmap = simpleDecoder.DecodeFromBytes(bytes, bytes.Length);
+                    Bitmap bitmap = simpleDecoder.DecodeFromBytes(bytes, bytes.LongLength);
 
                     Image thumbnail = bitmap.GetThumbnailImage(width, height, null, IntPtr.Zero);