diff --git a/ch1/ch1-02.md b/ch1/ch1-02.md
index 91476c4..9aceff2 100644
--- a/ch1/ch1-02.md
+++ b/ch1/ch1-02.md
@@ -101,6 +101,7 @@ package main
 
 import (
 	"fmt"
+    "os"
 )
 
 func main() {