diff --git a/.travis.yml b/.travis.yml
index b8824c4..472a3a7 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,7 +5,8 @@ install:
   - go get github.com/shaoshing/gotest
   - go get github.com/shaoshing/train
   - go get github.com/shaoshing/train/interpreter
-  - gem in sass
+  - gem in sass --pre
   - gem in coffee-script
 script:
+  cd $HOME/gopath/src/github.com/shaoshing/train
   ./test_all.sh
diff --git a/cmd/bundle_test.go b/cmd/bundle_test.go
index 2362a7a..bd36e40 100644
--- a/cmd/bundle_test.go
+++ b/cmd/bundle_test.go
@@ -16,7 +16,7 @@ func assertEqual(path, content string) {
 	if err != nil {
 		panic(err)
 	}
-	assert.Equal(content, string(c))
+	assert.Contain(content, string(c))
 }
 
 func TestCommand(t *testing.T) {
diff --git a/cmd/diagnose.go b/cmd/diagnose.go
index 7a9417d..4b7a5ed 100644
--- a/cmd/diagnose.go
+++ b/cmd/diagnose.go
@@ -11,7 +11,7 @@ import (
 func diagnose() bool {
 	var err error
 
-	fmt.Println("== Diagnosing\n")
+	fmt.Println("== Diagnosing")
 
 	var rubyVersion string
 	rubyVersion, err = bash(`ruby -e "puts RUBY_VERSION"`)
@@ -34,15 +34,19 @@ func diagnose() bool {
 	_, err = bash("gem which sass")
 	if err != nil {
 		fmt.Println("-- SASS is disabled because the required gem is not found.")
-		fmt.Println("   (install it if you wish to use SASS: gem install sass)\n")
+		fmt.Println("   (install it if you wish to use SASS: gem install sass)")
 		allGood = false
 	} else {
 		_, err = interpreter.Compile(assetsPath + "/stylesheets/font.sass")
 		if err != nil {
 			fmt.Println("-- SASS is disabled because error raised while compiling. Error:")
 			fmt.Printf("%s\n", err.Error())
-			fmt.Println("(this might related to your Ruby Environment; try re-installing Ruby)\n")
+			fmt.Println("(this might related to your Ruby Environment; try re-installing Ruby)")
 			allGood = false
+		} else {
+			sassVersion, _ := bash(`ruby -e "require 'sass'; puts Sass::VERSION"`)
+			supportSourceMap, _ := bash(`ruby -e 'require "sass"; e = Sass::Engine.new ""; puts(e.respond_to?(:render_with_sourcemap) ? "yes" : "no")'`)
+			fmt.Printf("-- SASS [supported] version: %s, sourcemap: %s\n", strings.Trim(sassVersion, "\n"), strings.Trim(supportSourceMap, "\n"))
 		}
 	}
 
@@ -56,8 +60,11 @@ func diagnose() bool {
 		if err != nil {
 			fmt.Println("-- CoffeeScript is disabled because error raised while compiling. Error: ")
 			fmt.Printf("%s\n", err.Error())
-			fmt.Println("(this might related to your Ruby Environment; try re-installing Ruby)\n")
+			fmt.Println("(this might related to your Ruby Environment; try re-installing Ruby)")
 			allGood = false
+		} else {
+			coffeeVersion, _ := bash(`ruby -e "require 'coffee-script'; puts CoffeeScript.version"`)
+			fmt.Printf("-- Coffee [supported] version: %s\n", strings.Trim(coffeeVersion, "\n"))
 		}
 	}
 
diff --git a/handler.go b/handler.go
index a51a958..83eb56a 100644
--- a/handler.go
+++ b/handler.go
@@ -1,6 +1,7 @@
 package train
 
 import (
+	"github.com/shaoshing/train/interpreter"
 	"io"
 	"log"
 	"net/http"
@@ -18,6 +19,7 @@ func servePublicAssets(w http.ResponseWriter, r *http.Request) {
 var contentTypes = map[string]string{
 	".js":  "application/javascript",
 	".css": "text/css",
+	".map": "text/plain",
 }
 
 func serveAssets(w http.ResponseWriter, r *http.Request) {
@@ -40,6 +42,16 @@ func serveAssets(w http.ResponseWriter, r *http.Request) {
 			w.Header().Set("Content-Type", contentTypes[ext])
 			io.Copy(w, strings.NewReader(content))
 		}
+	case ".map":
+		filePath := strings.Replace(url, "/", "", 1)
+		sourcemap, err := interpreter.Compile(filePath)
+		if err != nil {
+			io.Copy(w, strings.NewReader(err.Error()))
+			log.Printf("Failed to compile sourcemap\nGET %s\n-----------------------\n%s\n", url, err.Error())
+		} else {
+			w.Header().Set("Content-Type", contentTypes[ext])
+			io.Copy(w, strings.NewReader(sourcemap))
+		}
 	default:
 		(*assetServer).ServeHTTP(w, r)
 	}
diff --git a/handler_test.go b/handler_test.go
index db09b8a..2417f51 100644
--- a/handler_test.go
+++ b/handler_test.go
@@ -56,6 +56,8 @@ h2 {
   color: green; }
 `, "text/css")
 
+	assertAsset("/assets/stylesheets/app.sass.map", `"file": "assets/stylesheets/app.css"`, "text/plain")
+
 	assertAsset("/assets/stylesheets/app2.css", `h2 {
   color: green; }
 
@@ -108,8 +110,8 @@ func get(url string) (body, contentType string, status int) {
 
 func assertAsset(url, expectedBody, expectedContentType string) {
 	body, contentType, _ := get(url)
-	assert.Equal(expectedBody, body)
-	assert.Equal(true, strings.Index(contentType, expectedContentType) != -1)
+	assert.Contain(expectedBody, body)
+	assert.True(strings.Index(contentType, expectedContentType) != -1)
 }
 
 func assert404(url string) {
diff --git a/interpreter/bridge.go b/interpreter/bridge.go
index 5018d48..8c6e7c0 100644
--- a/interpreter/bridge.go
+++ b/interpreter/bridge.go
@@ -41,7 +41,17 @@ func Compile(filePath string) (result string, err error) {
 		if e != nil {
 			panic(err)
 		}
-		result, err = interpreter.Render(strings.Replace(fileExt, ".", "", 1), content)
+		result, err = interpreter.Render(strings.Replace(fileExt, ".", "", 1), content, filePath)
+	case ".map":
+		filePath = strings.Replace(filePath, ".map", "", 1)
+		fileExt := path.Ext(filePath)
+		content, e := ioutil.ReadFile(filePath)
+		if e != nil {
+			panic(err)
+		}
+		result, err = interpreter.Render(strings.Replace(fileExt, ".", "", 1)+"_source_map", content, filePath)
+		wd, _ := os.Getwd()
+		result = strings.Replace(result, "../.."+wd, "", -1)
 	default:
 		err = errors.New("Unsupported format (" + filePath + "). Valid formats are: sass.")
 	}
@@ -49,7 +59,7 @@ func Compile(filePath string) (result string, err error) {
 	return
 }
 
-func (this *Interpreter) Render(format string, content []byte) (result string, err error) {
+func (this *Interpreter) Render(format string, content []byte, filePath string) (result string, err error) {
 	this.Lock()
 	defer this.Unlock()
 
@@ -62,7 +72,7 @@ func (this *Interpreter) Render(format string, content []byte) (result string, e
 
 	option := getOption()
 
-	conn.Write([]byte(format + "<<" + option + "<<" + string(content)))
+	conn.Write([]byte(format + "<<" + option + "<<" + string(content) + "<<" + filePath))
 	var data bytes.Buffer
 	data.ReadFrom(conn)
 	conn.Close()
diff --git a/interpreter/bridge_test.go b/interpreter/bridge_test.go
index fd7809b..c5d3499 100644
--- a/interpreter/bridge_test.go
+++ b/interpreter/bridge_test.go
@@ -38,6 +38,9 @@ func TestSass(t *testing.T) {
 	Config.SASS.LineNumbers = true
 	css, e = Compile("assets/stylesheets/app.sass")
 	assert.Contain("line 1", css)
+
+	css, e = Compile("assets/stylesheets/app.sass.map")
+	assert.Contain(`"file": "assets/stylesheets/app.css"`, css)
 }
 
 func TestCoffee(t *testing.T) {
diff --git a/interpreter/interpreter.rb b/interpreter/interpreter.rb
index bb687c6..26b8b55 100644
--- a/interpreter/interpreter.rb
+++ b/interpreter/interpreter.rb
@@ -10,10 +10,10 @@ def self.serve
     server = listen
     loop do
       client = server.accept
-      format, option, content = read_all(client)
+      format, option, content, file_path = read_all(client)
 
       begin
-        result = self.send("render_#{format}", content, option)
+        result = self.send("render_#{format}", content, option, file_path)
         client.write "success<<#{result}"
       rescue Exception => e
         puts e
@@ -71,15 +71,19 @@ def self.read_all client
    data.split("<<")
   end
 
-  def self.render_sass content, option
-    _render_sass(content, :sass, option)
+  def self.render_sass content, option, file_path
+    _render_sass(content, :sass, option, file_path)
   end
 
-  def self.render_scss content, option
-    _render_sass(content, :scss, option)
+  def self.render_scss content, option, file_path
+    _render_sass(content, :scss, option, file_path)
   end
 
-  def self._render_sass content, syntax, option
+  def self.render_sass_source_map content, option, file_path
+    _render_sass(content, :scss, "source_map", file_path)
+  end
+
+  def self._render_sass content, syntax, option, file_path
     require "sass"
 
     options = {
@@ -89,12 +93,31 @@ def self._render_sass content, syntax, option
 
     options[:debug_info] = true if option == "debug_info"
     options[:line_numbers] = true if option == "line_numbers"
-
+    options[:filename] = file_path
     engine = Sass::Engine.new(content, options)
-    engine.render
+
+    css_uri = file_path.sub(/\.(scss|sass)/, ".css")
+    @source_map ||= {}
+    return @source_map[css_uri] if option == "source_map" && @source_map[css_uri]
+
+    if engine.respond_to?(:render_with_sourcemap)
+      source_map_uri = "/" + file_path + ".map"
+      results = engine.render_with_sourcemap(source_map_uri)
+      css = results[0]
+      source_map = results[1].to_json(:css_uri => css_uri, :sourcemap_path => source_map_uri)
+
+      @source_map[css_uri] = source_map
+      option == "source_map" ? @source_map[css_uri] : css
+    else
+      if option == "source_map"
+        raise "Please install sass pre-released SASS version (gem in sass --pre) to get support of sourcemap"
+      end
+
+      engine.render
+    end
   end
 
-  def self.render_coffee content, option
+  def self.render_coffee content, option, file_path
     require "coffee-script"
     CoffeeScript.compile content
   end