diff --git a/db.go b/db.go
index 3b88426..8fa45f9 100644
--- a/db.go
+++ b/db.go
@@ -26,7 +26,7 @@ import (
 	_ "github.com/mattn/go-sqlite3"
 )
 
-type insertFunc func(date, baseURL string) error
+type insertFunc func(date, baseUrl string) error
 type queryFunc func(num int) ([]picture, error)
 type checkFunc func(date string) (bool, error)
 
@@ -56,8 +56,8 @@ func newDbOperator(db *sql.DB, table string) (*dbOperator, error) {
 	}
 
 	return &dbOperator{
-		insert: func(date, baseURL string) error {
-			_, err := insertCmd.Exec(date, baseURL)
+		insert: func(date, baseUrl string) error {
+			_, err := insertCmd.Exec(date, baseUrl)
 			return err
 		},
 
@@ -71,7 +71,7 @@ func newDbOperator(db *sql.DB, table string) (*dbOperator, error) {
 			}
 
 			for result.Next() {
-				err := result.Scan(&pic.Date, &pic.BaseURL)
+				err := result.Scan(&pic.Date, &pic.BaseUrl)
 				if err != nil {
 					return nil, err
 				}
diff --git a/handler.go b/handler.go
index 6ecd45a..a733ee9 100644
--- a/handler.go
+++ b/handler.go
@@ -76,9 +76,9 @@ func (h *handler) updatePics() bool {
 		return false
 	}
 
-	for i := range pics {
+	for i := len(pics) - 1; i > -1; i-- {
 		if ok, _ := h.db.check(pics[i].Date); ok {
-			h.db.insert(pics[i].Date, pics[i].BaseURL)
+			h.db.insert(pics[i].Date, pics[i].BaseUrl)
 		}
 	}
 	return true
@@ -97,7 +97,6 @@ func (h *handler) updateBuff() bool {
 }
 
 func (h *handler) updateTask(dur int, wg *sync.WaitGroup) {
-	wg.Add(1)
 	first := true
 	timer := time.NewTimer(0)
 	for {
@@ -138,7 +137,7 @@ func (h *handler) redirect(w http.ResponseWriter, r *http.Request) {
 	} else {
 		pic = h.pic[h.picNum-1]
 	}
-	url.WriteString(pic.BaseURL)
+	url.WriteString(pic.BaseUrl)
 
 	if h.withres {
 		res, ok := args["res"]
diff --git a/main.go b/main.go
index 7bcd04e..481adf0 100644
--- a/main.go
+++ b/main.go
@@ -61,6 +61,7 @@ func init() {
 		panic("CreateHandlerError")
 	}
 
+	wg.Add(2)
 	go bingHandler.updateTask(conf.UpdateTime, &wg)
 	go apodHandler.updateTask(conf.UpdateTime, &wg)
 }
diff --git a/origin.go b/origin.go
index 2b52dd0..09d11e2 100644
--- a/origin.go
+++ b/origin.go
@@ -24,13 +24,14 @@ import (
 	"io/ioutil"
 	"net/http"
 	"regexp"
+	"strconv"
 	"strings"
 	"time"
 )
 
 type picture struct {
 	Date    string `json:"enddate"`
-	BaseURL string `json:"urlbase"`
+	BaseUrl string `json:"urlbase"`
 }
 
 func httpGet(url string) ([]byte, bool) {
@@ -48,9 +49,14 @@ func httpGet(url string) ([]byte, bool) {
 }
 
 func getBing(num int) ([]picture, bool) {
-	url := bing + "/HPImageArchive.aspx?format=js&n=2&mkt=zh-CN"
+	var url strings.Builder
+	url.Grow(192)
+	url.WriteString(bing)
+	url.WriteString("/HPImageArchive.aspx?format=js&n=")
+	url.WriteString(strconv.Itoa(num))
+	url.WriteString("&mkt=zh-CN")
 
-	msg, ok := httpGet(url)
+	msg, ok := httpGet(url.String())
 	if !ok {
 		return nil, false
 	}
@@ -72,7 +78,7 @@ func getAPOD(num int) ([]picture, bool) {
 	date := time.Now()
 	matcher := regexp.MustCompile(`image/.*\.jpg`)
 
-	for i := 0; i < 100; i++ {
+	for i := 0; i < num; i++ {
 		date = date.AddDate(0, 0, -1)
 
 		url.Reset()
@@ -92,13 +98,13 @@ func getAPOD(num int) ([]picture, bool) {
 			continue
 		}
 
-		baseURL := matcher.FindAll(msg, -1)
-		if baseURL == nil {
+		baseUrl := matcher.FindAll(msg, -1)
+		if baseUrl == nil {
 			continue
 		}
 		ret = append(ret, picture{
 			Date:    date.Format("20060102"),
-			BaseURL: string(baseURL[1]),
+			BaseUrl: string(baseUrl[1]),
 		})
 	}
 	return ret, true