diff --git a/books/free-programming-books-zh.md b/books/free-programming-books-zh.md
index 70e340267..8ee8e178c 100644
--- a/books/free-programming-books-zh.md
+++ b/books/free-programming-books-zh.md
@@ -329,8 +329,8 @@
 * [100个gcc小技巧](https://github.com/hellogcc/100-gcc-tips/blob/master/src/index.md)
 * [100个gdb小技巧](https://github.com/hellogcc/100-gdb-tips/blob/master/src/index.md)
 * [简单易懂的C魔法](https://web.archive.org/web/20210413213859/http://www.nowamagic.net/librarys/books/contents/c) *(:card_file_box: archived)*
-* [现代 C++ 并发编程教程](https://github.com/Mq-b/ModernCpp-ConcurrentProgramming-Tutorial)
-* [现代 C++ 模板教程](https://github.com/Mq-b/Modern-Cpp-templates-tutorial)
+* [现代 C++ 并发编程教程](https://github.com/Mq-b/ModernCpp-ConcurrentProgramming-Tutorial/tree/main/md)
+* [现代 C++ 模板教程](https://github.com/Mq-b/Modern-Cpp-templates-tutorial/tree/main/md)
 * [現代 C++ 101](https://hackmd.io/@lumynou5/CppTutorial-zh-tw) - Lumynous (:construction: *in process*)
 * [像计算机科学家一样思考（C++版)](http://www.ituring.com.cn/book/1203) (《How To Think Like a Computer Scientist: C++ Version》中文版)
 * [C 语言编程透视](https://tinylab.gitbooks.io/cbook/content/)