diff --git a/README.md b/README.md
index 99871d9..c2e4721 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,8 @@
 # C-JS-bytebeat-render
 
+> **Note**
+> This mirror is outdated due to technical issues.
+
 **Description:** a bytebeat rendering engine in C (no support of JavaScript
 bytebeat yet)