diff --git a/ch5/ch5-05.md b/ch5/ch5-05.md
index 62c3ef8..41c4b78 100644
--- a/ch5/ch5-05.md
+++ b/ch5/ch5-05.md
@@ -122,6 +122,6 @@ $ ./outline2 http://gopl.io
 
 練習 **5.9** ：編寫函數 expand,將s中的"foo"替換爲f("foo")的返迴值。
 
-```go
+```Go
 	func expand(s string, f func(string) string) string
 ```
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