diff --git a/Emby.Naming/Video/StackResolver.cs b/Emby.Naming/Video/StackResolver.cs
index 8119a02674..6a07561a06 100644
--- a/Emby.Naming/Video/StackResolver.cs
+++ b/Emby.Naming/Video/StackResolver.cs
@@ -132,7 +132,7 @@ namespace Emby.Naming.Video
             }
         }
 
-        private class StackMetadata
+        private sealed class StackMetadata
         {
             public StackMetadata(bool isDirectory, bool isNumerical, string partType)
             {