diff --git a/api.go b/api.go
index 3f08a16..fd36e62 100644
--- a/api.go
+++ b/api.go
@@ -3,20 +3,15 @@ package main
 import (
 	"errors"
 	"fmt"
+	"mime"
 	"path/filepath"
 	"strings"
 
 	"github.com/gin-gonic/gin"
 )
 
-var MIME_TYPES = map[string]string{
-	".css":  "text/css",
-	".js":   "application/javascript",
+var extraMimeTypes = map[string]string{
 	".icon": "image-x-icon",
-	".eot":  "application/vnd.ms-fontobject",
-	".svg":  "image/svg+xml",
-	".ttf":  "application/font-sfnt",
-	".woff": "application/font-woff",
 }
 
 type Error struct {
@@ -28,13 +23,18 @@ func NewError(err error) Error {
 }
 
 func assetContentType(name string) string {
-	mime := MIME_TYPES[filepath.Ext(name)]
+	ext := filepath.Ext(name)
+	result := mime.TypeByExtension(ext)
 
-	if mime != "" {
-		return mime
-	} else {
-		return "text/plain"
+	if result == "" {
+		result = extraMimeTypes[ext]
 	}
+
+	if result == "" {
+		result = "text/plain; charset=utf-8"
+	}
+
+	return result
 }
 
 func setupRoutes(router *gin.Engine) {
diff --git a/api_test.go b/api_test.go
new file mode 100644
index 0000000..d7b58a8
--- /dev/null
+++ b/api_test.go
@@ -0,0 +1,29 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_assetContentType(t *testing.T) {
+	samples := map[string]string{
+		"foo.html": "text/html; charset=utf-8",
+		"foo.css":  "text/css; charset=utf-8",
+		"foo.js":   "application/javascript",
+		"foo.icon": "image-x-icon",
+		"foo.png":  "image/png",
+		"foo.jpg":  "image/jpeg",
+		"foo.gif":  "image/gif",
+		"foo.eot":  "application/vnd.ms-fontobject",
+		"foo.svg":  "image/svg+xml",
+		"foo.ttf":  "application/x-font-ttf",
+		"foo.woff": "application/x-font-woff",
+		"foo.foo":  "text/plain; charset=utf-8",
+		"foo":      "text/plain; charset=utf-8",
+	}
+
+	for name, expected := range samples {
+		assert.Equal(t, expected, assetContentType(name))
+	}
+}