diff --git a/src/modules/coupons/providers/coupon.service.ts b/src/modules/coupons/providers/coupon.service.ts
index 62a04ed..d99ecfe 100644
--- a/src/modules/coupons/providers/coupon.service.ts
+++ b/src/modules/coupons/providers/coupon.service.ts
@@ -244,7 +244,7 @@ export class CouponService {
     for (let i = 0; i < bytes.length; i++) {
       result += chars[bytes[i] % chars.length];
     }
-    const prefix = restaurantSlug.slice(0, 2);
+    const prefix = restaurantSlug.slice(0, 2).toUpperCase();
     return prefix + '-' + result;
   }