diff --git a/cmd/getdoc/main.go b/cmd/getdoc/main.go
index 1e3ce4c..8aea552 100644
--- a/cmd/getdoc/main.go
+++ b/cmd/getdoc/main.go
@@ -17,6 +17,7 @@ import (
 func main() {
 	dir := flag.String("dir", filepath.Join(os.TempDir(), "getdoc"), "working directory")
 	outDir := flag.String("out-dir", "", "path to write schema")
+	host := flag.String("host", "core.telegram.org", "host")
 	outFile := flag.String("out-file", "", "filename of schema")
 	readonly := flag.Bool("readonly", false, "read-only mode")
 	pretty := flag.Bool("pretty", false, "pretty json output")
@@ -24,6 +25,7 @@ func main() {
 
 	client, err := dl.NewClient(dl.Options{
 		Path:     filepath.Join(*dir, "cache"),
+		Host:     *host,
 		Readonly: *readonly,
 	})
 	if err != nil {
diff --git a/dl/dl.go b/dl/dl.go
index e50035f..3b69d2d 100644
--- a/dl/dl.go
+++ b/dl/dl.go
@@ -20,11 +20,13 @@ type Client struct {
 	rate     ratelimit.Limiter
 	http     HTTPClient
 	cache    cache.Cacher
+	host     string
 	readonly bool
 }
 
 type Options struct {
 	Client   HTTPClient
+	Host     string
 	Path     string
 	Readonly bool
 	FromZip  bool
@@ -38,10 +40,14 @@ func NewClient(opt Options) (*Client, error) {
 	if opt.Client == nil {
 		opt.Client = http.DefaultClient
 	}
+	if opt.Host == "" {
+		opt.Host = "core.telegram.org"
+	}
 
 	c := &Client{
 		http:     opt.Client,
 		readonly: opt.Readonly,
+		host:     opt.Host,
 		rate:     ratelimit.New(10),
 	}
 
@@ -72,7 +78,7 @@ func (c *Client) download(ctx context.Context, layer int, key string) ([]byte, e
 	// `stel_dev_layer=117`
 	u := &url.URL{
 		Scheme: "https",
-		Host:   "core.telegram.org",
+		Host:   c.host,
 		Path:   key,
 	}
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, u.String(), http.NoBody)