diff --git a/core/api_coupon.go b/core/api_coupon.go
index 8bf12ef..18bda65 100644
--- a/core/api_coupon.go
+++ b/core/api_coupon.go
@@ -320,7 +320,7 @@ func useCoupon(mongoClient gocommon.MongoClient, w http.ResponseWriter, r *http.
 			"_id": roundObj,
 		}, bson.M{
 			"$push": bson.M{"used": key},
-		}, &coupon, options.FindOneAndUpdate().SetProjection(bson.M{"effect": 1})); err != nil {
+		}, &coupon, options.FindOneAndUpdate().SetProjection(bson.M{"effect": 1, "expire": 1})); err != nil {
 			logger.Println(err)
 			w.WriteHeader(http.StatusInternalServerError)
 			return