diff --git a/cmd/main.go b/cmd/main.go
index fcf25cb..8c6d172 100644
--- a/cmd/main.go
+++ b/cmd/main.go
@@ -212,5 +212,6 @@ func getNewApp(log logger.T, v config.SubConfigT) (app.Option, error) {
 		C:                  cch,
 		L:                  logger.NewLayer(log, fmt.Sprintf("[%s] app", v.Name)),
 		DefaultVideoHeight: v.DefaultVideoHeight,
+		MaxVideoHeight:     v.MaxVideoHeight,
 	}, nil
 }
diff --git a/config.example.jsonc b/config.example.jsonc
index fbc66d3..61d50d7 100644
--- a/config.example.jsonc
+++ b/config.example.jsonc
@@ -9,9 +9,12 @@
     // web server listen port.
     // DEFAULT 8080
     "port": 8080,
-    // used if video height not set in request
+    // used if video height not set in request.
     // DEFAULT 720
     "default-video-height": 360,
+    // restrict maximum video height.
+    // DEFAULT 720
+    "max-video-height": 1080,
     // logger config
     "log": {
         // log level
@@ -139,6 +142,7 @@
                 "my.streamer.example"
             ],
             "default-video-height": 1080,
+            "max-video-height": 1080,
             "extractor": {
                 "path": "direct"
             },
diff --git a/lib/app/app.go b/lib/app/app.go
index afcf51b..aaa5204 100644
--- a/lib/app/app.go
+++ b/lib/app/app.go
@@ -28,7 +28,8 @@ type app struct {
 	name               string
 	sites              []string
 	log                logger.T
-	defaultVideoHeight uint16
+	defaultVideoHeight uint64
+	maxVideoHeight     uint64
 }
 
 type AppLogic struct {
@@ -45,7 +46,8 @@ type Option struct {
 	S                  streamer.T
 	C                  cache.T
 	L                  logger.T
-	DefaultVideoHeight uint16
+	DefaultVideoHeight uint64
+	MaxVideoHeight     uint64
 }
 
 func New(log logger.T, def Option, opts []Option) *AppLogic {
@@ -63,6 +65,7 @@ func (t *AppLogic) set(log logger.T, def Option, opts []Option) {
 		extractor:          def.X,
 		streamer:           def.S,
 		defaultVideoHeight: def.DefaultVideoHeight,
+		maxVideoHeight:     def.MaxVideoHeight,
 	}
 
 	t.appList = make([]app, 0)
@@ -75,6 +78,7 @@ func (t *AppLogic) set(log logger.T, def Option, opts []Option) {
 			sites:              v.Sites,
 			log:                v.L,
 			defaultVideoHeight: v.DefaultVideoHeight,
+			maxVideoHeight:     v.MaxVideoHeight,
 		})
 	}
 }
@@ -199,11 +203,19 @@ func parseQuery(query string) (string, uint64, string) {
 }
 
 func (t *app) fixRequest(link string, height uint64, format string) extractor_config.RequestT {
-	var h string
-	if height == 0 {
-		h = fmt.Sprintf("%d", t.defaultVideoHeight)
-	} else {
-		h = fmt.Sprintf("%d", height)
+	var (
+		h   string
+		toS = func(d uint64) string {
+			return fmt.Sprintf("%d", d)
+		}
+	)
+	switch {
+	case height == 0:
+		h = toS(t.defaultVideoHeight)
+	case height > t.maxVideoHeight:
+		h = toS(t.maxVideoHeight)
+	default:
+		h = toS(height)
 	}
 	return extractor_config.RequestT{
 		URL:    link,
diff --git a/lib/config/config.go b/lib/config/config.go
index 801fe41..beabfa4 100644
--- a/lib/config/config.go
+++ b/lib/config/config.go
@@ -15,7 +15,8 @@ import (
 type ConfigT struct {
 	PortInt            uint16                   `json:"port"`
 	Host               string                   `json:"host"`
-	DefaultVideoHeight uint16                   `json:"default-video-height"`
+	DefaultVideoHeight uint64                   `json:"default-video-height"`
+	MaxVideoHeight     uint64                   `json:"max-video-height"`
 	Streamer           streamer.ConfigT         `json:"streamer"`
 	Extractor          extractor_config.ConfigT `json:"extractor"`
 	Log                logger_config.ConfigT    `json:"log"`
@@ -53,6 +54,7 @@ func defaultConfig() ConfigT {
 		PortInt:            8080,
 		Host:               "0.0.0.0",
 		DefaultVideoHeight: 720,
+		MaxVideoHeight:     720,
 		Streamer: streamer.ConfigT{
 			EnableErrorHeaders:   &fls,
 			IgnoreMissingHeaders: &fls,
@@ -96,6 +98,9 @@ func appendConfig(src ConfigT, dst ConfigT) ConfigT {
 	if dst.DefaultVideoHeight == 0 {
 		dst.DefaultVideoHeight = src.DefaultVideoHeight
 	}
+	if dst.MaxVideoHeight == 0 {
+		dst.MaxVideoHeight = src.MaxVideoHeight
+	}
 	// streamer
 	if dst.Streamer.EnableErrorHeaders == nil {
 		dst.Streamer.EnableErrorHeaders = src.Streamer.EnableErrorHeaders