diff --git a/src/lib/datasource/S3.ts b/src/lib/datasource/S3.ts
index 9af7194d8..5b95523ee 100644
--- a/src/lib/datasource/S3.ts
+++ b/src/lib/datasource/S3.ts
@@ -64,7 +64,7 @@ export class S3Datasource extends Datasource {
     this.ensureReadWriteAccess();
   }
 
-  private key(path: string): string {
+  public key(path: string): string {
     if (this.options.subdirectory) {
       return this.options.subdirectory.endsWith('/')
         ? this.options.subdirectory + path
diff --git a/src/offload/partial.ts b/src/offload/partial.ts
index 5c918e90d..caa1152cd 100755
--- a/src/offload/partial.ts
+++ b/src/offload/partial.ts
@@ -152,7 +152,7 @@ async function main() {
         client: s3datasource.client,
         params: {
           Bucket: s3datasource.options.bucket,
-          Key: file.filename,
+          Key: s3datasource.key(file.filename),
           Body: bodyStream,
         },
         partSize: bytes(config.chunks.size),