diff --git a/karma.conf.unit.js b/karma.conf.unit.js
index 7d3fd56..3fe64bd 100644
--- a/karma.conf.unit.js
+++ b/karma.conf.unit.js
@@ -3,12 +3,10 @@
  * @author fe.xiaowu@gmail.com
  */
 
-const base = require('./karma.conf.base.js');
+var base = require('./karma.conf.base.js');
 
 module.exports = function(config) {
-    const options = Object.assign(base(config), {
-
-    });
+    var options = Object.assign(base(config), {});
 
     config.set(options);
 };
\ No newline at end of file