diff --git a/buds/02.md b/buds/02.md
index e491892..fa073b0 100644
--- a/buds/02.md
+++ b/buds/02.md
@@ -42,7 +42,15 @@ The endpoint MUST NOT modify the blob in any way and should return the exact sam
 
 The endpoint MUST return a [Blob Descriptor](#blob-descriptor) if the upload was successful or an error object if it was not
 
-Servers MAY reject an upload for any reason and should respond with the appropriate HTTP `4xx` status code and an error message explaining the reason for the rejection
+Servers MAY reject an upload for any reason and should respond with the appropriate HTTP `4xx` status code and an error
+message explaining the reason for the rejection
+
+### File extension normalization (Optional)
+
+When storing blobs, servers MAY normalise the file extension to a standard format (e.g. `.pdf`, `.png`, etc.) based on
+the MIME type of the blob. This can be especially useful when the `GET /<sha256>` endpoint is redirected to an external
+URL (see the [proxying and redirection section from BUD-01](./01.md#proxying-and-redirection-optional)), as external
+servers may rely on the file extension to serve the blob correctly.
 
 ### Upload Authorization (Optional)