diff --git a/courses/free-courses-si.md b/courses/free-courses-si.md
index 1aaa48e4f..030844903 100644
--- a/courses/free-courses-si.md
+++ b/courses/free-courses-si.md
@@ -1,6 +1,6 @@
 ### Index
 
-* [ASP.NET Core](#aspnet_core)
+* [ASP.NET Core](#aspnet-core)
 * [HTML and CSS](#html-and-css)
 * [Java](#java)
 * [JavaScript](#javascript)