diff --git a/ch_0/hello_world.cpp b/ch_0/hello_world/main.cpp
similarity index 58%
rename from ch_0/hello_world.cpp
rename to ch_0/hello_world/main.cpp
index 5a2267d..ad8283b 100644
--- a/ch_0/hello_world.cpp
+++ b/ch_0/hello_world/main.cpp
@@ -1,6 +1,6 @@
 #include <iostream>
 
 int main() {
-    std::cout << "Hello World!\n";
+    std::cout << "Hello, World!\n";
     return 0;
 }