diff --git a/render/html.go b/render/html.go
index de2320b..e8e1305 100644
--- a/render/html.go
+++ b/render/html.go
@@ -26,6 +26,8 @@ type (
 	}
 )
 
+const htmlContentType = "text/html; charset=utf-8"
+
 func (r HTMLProduction) Instance(name string, data interface{}) Render {
 	return HTML{
 		Template: r.Template,
@@ -52,6 +54,6 @@ func (r HTMLDebug) loadTemplate() *template.Template {
 }
 
 func (r HTML) Write(w http.ResponseWriter) error {
-	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	w.Header().Set("Content-Type", htmlContentType)
 	return r.Template.ExecuteTemplate(w, r.Name, r.Data)
 }
diff --git a/render/json.go b/render/json.go
index 5718539..502a74e 100644
--- a/render/json.go
+++ b/render/json.go
@@ -15,13 +15,15 @@ type (
 	}
 )
 
+const jsonContentType = "application/json; charset=utf-8"
+
 func (r JSON) Write(w http.ResponseWriter) error {
-	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Header().Set("Content-Type", jsonContentType)
 	return json.NewEncoder(w).Encode(r.Data)
 }
 
 func (r IndentedJSON) Write(w http.ResponseWriter) error {
-	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Header().Set("Content-Type", jsonContentType)
 	jsonBytes, err := json.MarshalIndent(r.Data, "", "    ")
 	if err != nil {
 		return err
diff --git a/render/text.go b/render/text.go
index 020d213..4e38224 100644
--- a/render/text.go
+++ b/render/text.go
@@ -10,10 +10,12 @@ type String struct {
 	Data   []interface{}
 }
 
+const plainContentType = "text/plain; charset=utf-8"
+
 func (r String) Write(w http.ResponseWriter) error {
 	header := w.Header()
 	if _, exist := header["Content-Type"]; !exist {
-		header.Set("Content-Type", "text/plain; charset=utf-8")
+		header.Set("Content-Type", plainContentType)
 	}
 	if len(r.Data) > 0 {
 		fmt.Fprintf(w, r.Format, r.Data...)
diff --git a/render/xml.go b/render/xml.go
index 2002e61..d533f0e 100644
--- a/render/xml.go
+++ b/render/xml.go
@@ -9,7 +9,9 @@ type XML struct {
 	Data interface{}
 }
 
+const xmlContentType = "application/xml; charset=utf-8"
+
 func (r XML) Write(w http.ResponseWriter) error {
-	w.Header().Set("Content-Type", "application/xml; charset=utf-8")
+	w.Header().Set("Content-Type", xmlContentType)
 	return xml.NewEncoder(w).Encode(r.Data)
 }