diff --git a/book/en-us/04-containers.md b/book/en-us/04-containers.md
index bdfe638..0f04375 100644
--- a/book/en-us/04-containers.md
+++ b/book/en-us/04-containers.md
@@ -292,7 +292,7 @@ This will iterate over the tuple:
 ```cpp
 for(int i = 0; i != tuple_len(new_tuple); ++i)
     // runtime indexing
-    std::cout << tuple_index(i, new_tuple) << std::endl;
+    std::cout << tuple_index(new_tuple, i) << std::endl;
 ```
 
 ## Conclusion
diff --git a/book/zh-cn/04-containers.md b/book/zh-cn/04-containers.md
index a9999a6..d39205d 100644
--- a/book/zh-cn/04-containers.md
+++ b/book/zh-cn/04-containers.md
@@ -292,7 +292,7 @@ auto tuple_len(T &tpl) {
 // 迭代
 for(int i = 0; i != tuple_len(new_tuple); ++i)
     // 运行期索引
-    std::cout << tuple_index(i, new_tuple) << std::endl;
+    std::cout << tuple_index(new_tuple, i) << std::endl;
 ```
 
 ## 总结