diff --git a/src/download.rs b/src/download.rs
index c86d801..830e9fb 100644
--- a/src/download.rs
+++ b/src/download.rs
@@ -45,6 +45,7 @@ impl DownloadingFile {
 
         let mut res = HttpResponse::build(StatusCode::OK);
 
+        res.insert_header((header::CONTENT_SECURITY_POLICY, "sandbox"));
         res.insert_header((header::CONTENT_TYPE, mime::APPLICATION_OCTET_STREAM));
         res.insert_header((
             header::CONTENT_DISPOSITION,