diff --git a/ch2-cgo/ch2-01-hello-cgo.md b/ch2-cgo/ch2-01-hello-cgo.md
index 9154a7b..92d3700 100644
--- a/ch2-cgo/ch2-01-hello-cgo.md
+++ b/ch2-cgo/ch2-01-hello-cgo.md
@@ -106,6 +106,7 @@ void SayHello(const char* s);
 // hello.c
 
 #include "hello.h"
+#include <stdio.h>
 
 void SayHello(const char* s) {
 	puts(s);