diff --git a/lib/application.js b/lib/application.js
index 97a3b5bd..2b61e0cd 100644
--- a/lib/application.js
+++ b/lib/application.js
@@ -44,7 +44,7 @@ module.exports = class Application {
    * watcher callback
    */
   _watcherCallBack(fileInfo){
-    const transpiler = this.options.transpiler;
+    let transpiler = this.options.transpiler;
     if(transpiler){
       if(!helper.isArray(transpiler)){
         transpiler = [transpiler];