diff --git a/en/04.5.md b/en/04.5.md
index 97eaecde..6a622b89 100644
--- a/en/04.5.md
+++ b/en/04.5.md
@@ -124,6 +124,7 @@ func postFile(filename string, targetUrl string) error {
         fmt.Println("error opening file")
         return err
     }
+    defer fh.Close()
 
     //iocopy
     _, err = io.Copy(fileWriter, fh)