diff --git a/src/email/email.service.ts b/src/email/email.service.ts
index ecb236e..44e5e2d 100644
--- a/src/email/email.service.ts
+++ b/src/email/email.service.ts
@@ -131,7 +131,7 @@ export class EmailService {
     const worksheet = workbook.worksheets[0];
 
     const data: any[] = [];
-    let headers: string[] = [];
+    const headers: string[] = [];
     worksheet.eachRow((row, rowNumber) => {
       const rowData: any = {};
       row.eachCell({ includeEmpty: true }, (cell, colNumber) => {