diff --git a/src/internal/upload/zip.ts b/src/internal/upload/zip.ts
index 5a92311..4b9c43b 100644
--- a/src/internal/upload/zip.ts
+++ b/src/internal/upload/zip.ts
@@ -44,7 +44,7 @@ export async function createZipUploadStream(
   for (const file of uploadSpecification) {
     if (file.sourcePath !== null) {
       // Add a normal file to the zip
-      zip.append(createReadStream(file.sourcePath), {
+      zip.file(file.sourcePath, {
         name: file.destinationPath
       })
     } else {