diff --git a/plugins/upload/guest-js/index.ts b/plugins/upload/guest-js/index.ts
index d2eced4e..26bc93b4 100644
--- a/plugins/upload/guest-js/index.ts
+++ b/plugins/upload/guest-js/index.ts
@@ -51,6 +51,10 @@ async function upload(
   });
 }
 
+/// Download file from given url.
+///
+/// Note that `filePath` currently must include the file name.
+/// Furthermore the progress events will report a total length of 0 if the server did not sent a `Content-Length` header or if the file is compressed.
 async function download(
   url: string,
   filePath: string,
diff --git a/plugins/upload/src/lib.rs b/plugins/upload/src/lib.rs
index 21154e89..c4a0d8c7 100644
--- a/plugins/upload/src/lib.rs
+++ b/plugins/upload/src/lib.rs
@@ -62,9 +62,7 @@ async fn download<R: Runtime>(
     }
 
     let response = request.send().await?;
-    let total = response.content_length().ok_or_else(|| {
-        Error::ContentLength(format!("Failed to get content length from '{url}'"))
-    })?;
+    let total = response.content_length().unwrap_or(0);
 
     let mut file = File::create(file_path).await?;
     let mut stream = response.bytes_stream();