diff --git a/doc/dev/framework-migration.md b/doc/dev/framework-migration.md
index b7008e8..1c0b70b 100644
--- a/doc/dev/framework-migration.md
+++ b/doc/dev/framework-migration.md
@@ -5,12 +5,12 @@
 - To access `/:abc`, use `r.PathValue("abc")`.
 - Want to associate arbitrary value with a request? Use `r.Context.Value()`.
 - Don't use `r.Response`. It's `nil`.
+- Only use the following HTTP status codes:
+  - 303 StatusSeeOther: set method to GET
+  - 307 StatusTemporaryRedirect: method and body not changed
+  - 308 StatusPermanentRedirect: method and body not changed
 
 ## todo
 
-- correct redirect status codes. currently i put in whatever.
-  - 303 StatusSeeOther: set method to GET
-  - 307 Temporary: method and body not changed
-  - 308 Permanent: method and body not changed
 - add limiter (maybe it should be in nginx)
 - add caching (maybe it should be in nginx)
diff --git a/main.go b/main.go
index 20b09bf..85b812f 100644
--- a/main.go
+++ b/main.go
@@ -226,7 +226,7 @@ func defineRoutes() *mux.Router {
 
 	// Legacy illust URL
 	router.HandleFunc("/member_illust.php", func(w http.ResponseWriter, r *http.Request) {
-		http.Redirect(w, r, "/artworks/"+utils.CompatRequest{Request: r}.Query("illust_id"), http.StatusFound)
+		http.Redirect(w, r, "/artworks/"+utils.CompatRequest{Request: r}.Query("illust_id"), http.StatusPermanentRedirect)
 	}).Methods("GET")
 
 	// Proxy routes
diff --git a/routes/rankingCalendar.go b/routes/rankingCalendar.go
index 3e63c97..63051b9 100644
--- a/routes/rankingCalendar.go
+++ b/routes/rankingCalendar.go
@@ -45,8 +45,7 @@ func RankingCalendarPicker(w http.ResponseWriter, r CompatRequest) error {
 	return utils.RedirectToRoute(w, r,"/rankingCalendar",  map[string]string{
 			"mode": mode,
 			"date": date,
-		
-	}, http.StatusFound)
+	})
 }
 
 func RankingCalendarPage(w http.ResponseWriter, r CompatRequest) error {
diff --git a/routes/tag.go b/routes/tag.go
index 3e83431..d05f932 100644
--- a/routes/tag.go
+++ b/routes/tag.go
@@ -69,5 +69,5 @@ func AdvancedTagPost(w http.ResponseWriter, r CompatRequest) error {
 		"tool":     r.Query("tool", r.FormValue("tool")),
 		"scd":      r.Query("scd", r.FormValue("scd")),
 		"ecd":      r.Query("ecd", r.FormValue("ecd")),
-	}, http.StatusFound)
+	})
 }
diff --git a/semgrep.yml b/semgrep.yml
index 7118985..8b3644e 100644
--- a/semgrep.yml
+++ b/semgrep.yml
@@ -146,3 +146,10 @@ rules:
   #   func $NAME(w http.ResponseWriter, r *http.Request) error {
   #     $...I
   #   }
+- id: rule-11
+  message: "Use StatusSeeOther or StatusPermanentRedirect"
+  languages: [go]
+  severity: WARNING
+  patterns:
+  - pattern: |
+      StatusFound
diff --git a/utils/compat.go b/utils/compat.go
index e36edb0..d02692c 100644
--- a/utils/compat.go
+++ b/utils/compat.go
@@ -55,12 +55,12 @@ func SendString(w http.ResponseWriter, text string) error {
 	return err
 }
 
-func RedirectToRoute(w http.ResponseWriter, r CompatRequest, path string, query_params map[string]string, code int) error {
+func RedirectToRoute(w http.ResponseWriter, r CompatRequest, path string, query_params map[string]string) error {
 	query := url.Values{}
 	for k, v := range query_params {
 		query.Add(k, v)
 	}
-	http.Redirect(w, r.Request, path+query.Encode(), code)
+	http.Redirect(w, r.Request, path+query.Encode(), http.StatusSeeOther)
 	return nil
 }