diff --git a/SDBD.Demo/Program.cs b/SDBD.Demo/Program.cs
index 8af4fee..6e42303 100644
--- a/SDBD.Demo/Program.cs
+++ b/SDBD.Demo/Program.cs
@@ -11,7 +11,7 @@ if(encode) {
     inputData
   );
   var outputData = codec.Encode(document);
-  File.WriteAllBytes($"{filename}.sbdb", outputData);
+  File.WriteAllBytes($"{filename}.sdbd", outputData);
 } else {
   var document = codec.Decode(inputData);
   File.WriteAllBytes(document.Metadata["content-name"], document.Data);