diff --git a/api.planx.uk/modules/send/utils/exportZip.test.ts b/api.planx.uk/modules/send/utils/exportZip.test.ts
index cce3cc64ca..48fe1ce7dd 100644
--- a/api.planx.uk/modules/send/utils/exportZip.test.ts
+++ b/api.planx.uk/modules/send/utils/exportZip.test.ts
@@ -7,7 +7,6 @@ jest.mock("fs", () => ({
   existsSync: () => true,
   unlinkSync: () => undefined,
   createWriteStream: () => undefined,
-  writeFileSync: () => undefined,
   rmSync: () => undefined,
 }));
 
diff --git a/api.planx.uk/modules/send/utils/exportZip.ts b/api.planx.uk/modules/send/utils/exportZip.ts
index 379f1bf9ec..4a15b9bef7 100644
--- a/api.planx.uk/modules/send/utils/exportZip.ts
+++ b/api.planx.uk/modules/send/utils/exportZip.ts
@@ -193,13 +193,9 @@ export class ExportZip {
     const s3Key = url.split("/").slice(-2).join("/");
     const decodedS3Key = decodeURIComponent(s3Key);
     const { body } = await getFileFromS3(decodedS3Key);
-    if (!body) {
-      throw new Error("file not found");
-    }
-    const filePath = path.join(this.tmpDir, name);
-    fs.writeFileSync(filePath, body as Buffer);
-    this.zip.addLocalFile(filePath);
-    fs.unlinkSync(filePath);
+    if (!body) throw new Error("file not found");
+
+    this.zip.addFile(name, body as Buffer);
   }
 
   toBuffer(): Buffer {