diff --git a/common/utils.go b/common/utils.go
index eb6678a..d540c2e 100644
--- a/common/utils.go
+++ b/common/utils.go
@@ -236,3 +236,8 @@ func StringToByteSlice(s string) []byte {
 	tmp2 := [3]uintptr{tmp1[0], tmp1[1], tmp1[1]}
 	return *(*[]byte)(unsafe.Pointer(&tmp2))
 }
+
+func RandomSleep() {
+	// Sleep for 0-3000 ms
+	time.Sleep(time.Duration(rand.Intn(3000)) * time.Millisecond)
+}
diff --git a/controller/user.go b/controller/user.go
index f38aeb7..309ce49 100644
--- a/controller/user.go
+++ b/controller/user.go
@@ -7,6 +7,7 @@ import (
 	"one-api/common"
 	"one-api/model"
 	"strconv"
+	"sync"
 
 	"github.com/gin-contrib/sessions"
 	"github.com/gin-gonic/gin"
@@ -789,7 +790,11 @@ type topUpRequest struct {
 	Key string `json:"key"`
 }
 
+var lock = sync.Mutex{}
+
 func TopUp(c *gin.Context) {
+	lock.Lock()
+	defer lock.Unlock()
 	req := topUpRequest{}
 	err := c.ShouldBindJSON(&req)
 	if err != nil {
diff --git a/model/redemption.go b/model/redemption.go
index 122661f..00ec76b 100644
--- a/model/redemption.go
+++ b/model/redemption.go
@@ -56,7 +56,7 @@ func Redeem(key string, userId int) (quota int, err error) {
 	if common.UsingPostgreSQL {
 		keyCol = `"key"`
 	}
-
+	common.RandomSleep()
 	err = DB.Transaction(func(tx *gorm.DB) error {
 		err := tx.Set("gorm:query_option", "FOR UPDATE").Where(keyCol+" = ?", key).First(redemption).Error
 		if err != nil {