diff --git a/courses/free-courses-ko.md b/courses/free-courses-ko.md
index e51e97311..e587913d6 100644
--- a/courses/free-courses-ko.md
+++ b/courses/free-courses-ko.md
@@ -1,10 +1,10 @@
 ### Index
 
-* [Algorithms & Data Structures](#algorithms-&-data-structures)
+* [Algorithms & Data Structures](#algorithms--data-structures)
 * [Android](#android)
 * [Arduino](#arduino)
-* [ASP.NET](#asp.net)
-* [C/C++](#c/c++)
+* [ASP.NET](#aspnet)
+* [C/C++](#cc)
 * [C#](#csharp)
 * [Circuit](#circuit)
 * [Deep Learning](#deep-learning)
@@ -17,8 +17,8 @@
 * [Java](#java)
 * [JavaScript](#javascript)
     * [AngularJS](#angularjs)
-    * [Node.js](#node.js)
-    * [React.js](#react.js)
+    * [Node.js](#nodejs)
+    * [React.js](#reactjs)
 * [Kotlin](#kotlin)
 * [Linux](#linux)
 * [Machine Learning](#machine-learning)