diff --git a/README.md b/README.md
index 438d9a1..9a281f9 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # code2img [![PkgGoDev](https://pkg.go.dev/badge/golang.design/x/code2img)](https://pkg.go.dev/golang.design/x/code2img) ![](https://changkun.de/urlstat?mode=github&repo=golang-design/code2img)
 
-a carbon service wrapper for Go users
+A carbon-now wrapper for Go users and supports for iOS Shortcut
 
 ```go
 import "golang.design/x/code2img"
diff --git a/cmd/code2img/main.go b/cmd/code2img/main.go
index fae604a..f7d9466 100644
--- a/cmd/code2img/main.go
+++ b/cmd/code2img/main.go
@@ -47,7 +47,7 @@ func main() {
 		ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
 		defer cancel()
 
-		buf, err := code2img.Render(ctx, b.Code)
+		buf, err := code2img.Render(ctx, code2img.LangGo, b.Code)
 		if err != nil {
 			c.String(http.StatusBadRequest, fmt.Sprintf("Error: %s", err))
 			return
diff --git a/code2img.go b/code2img.go
index cbe111d..d6d8f30 100644
--- a/code2img.go
+++ b/code2img.go
@@ -19,9 +19,19 @@ import (
 	"github.com/chromedp/chromedp"
 )
 
+// Lang is represents a language
+type Lang string
+
+// All kinds of languages
+const (
+	LangAuto Lang = "auto"
+	LangGo   Lang = "text/x-go"
+	LangDiff Lang = "text/x-diff"
+)
+
 // Render renders the given code string and returns a binary buffer
 // that contains a carbon-now based image.
-func Render(ctx context.Context, code string) ([]byte, error) {
+func Render(ctx context.Context, lang Lang, code string) ([]byte, error) {
 	// https://carbon.now.sh/?
 	// bg=rgba(74%2C144%2C226%2C1)&
 	// t=material&
@@ -43,11 +53,15 @@ func Render(ctx context.Context, code string) ([]byte, error) {
 	// es=2x&
 	// wm=false&
 	// code=func%2520main()
+	if _, ok := supportedLang[lang]; !ok {
+		lang = LangAuto
+	}
+
 	var carbonOptions = map[string]string{
 		"bg":     "rgba(74,144,226,1)", // backgroundColor
 		"t":      "material",           // theme
 		"wt":     "none",               // windowTheme
-		"l":      "auto",               // language
+		"l":      string(lang),         // language
 		"ds":     "true",               // dropShadow
 		"dsyoff": "0px",                // dropShadowOffsetY
 		"dsblur": "29px",               // dropShadowBlurRadius
@@ -146,3 +160,11 @@ func screenshot(sel interface{}, picbuf *[]byte, opts ...chromedp.QueryOption) c
 		return nil
 	}, append(opts, chromedp.NodeVisible)...)
 }
+
+// if we need more languages, see:
+// https://github.com/carbon-app/carbon/blob/c2357e63efb60330f1c9ef84be4df2e8e94f661c/lib/constants.js
+var supportedLang = map[Lang]int{
+	LangAuto: 0,
+	LangGo:   0,
+	LangDiff: 0,
+}
diff --git a/code2img_test.go b/code2img_test.go
index 6550e8d..50b5392 100644
--- a/code2img_test.go
+++ b/code2img_test.go
@@ -22,7 +22,7 @@ func TestRender(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
 	defer cancel()
 
-	got, err := code2img.Render(ctx, `import "golang.design/x/code2img"`)
+	got, err := code2img.Render(ctx, code2img.LangGo, `import "golang.design/x/code2img"`)
 	if err != nil {
 		t.Fatalf("render failed: %v", err)
 	}
diff --git a/example/code.png b/example/code.png
index 89389a3..afd09c6 100644
Binary files a/example/code.png and b/example/code.png differ
diff --git a/example/main.go b/example/main.go
index d7ee9be..aa7a090 100644
--- a/example/main.go
+++ b/example/main.go
@@ -15,7 +15,7 @@ func main() {
 	code := string(f)
 
 	// render it!
-	b, err := code2img.Render(context.TODO(), code)
+	b, err := code2img.Render(context.TODO(), code2img.LangGo, code)
 	if err != nil {
 		panic(err)
 	}