diff --git a/source/13-sky-box-and-some-optimizations.md b/source/13-sky-box-and-some-optimizations.md
index f9331dd..48d80ee 100644
--- a/source/13-sky-box-and-some-optimizations.md
+++ b/source/13-sky-box-and-some-optimizations.md
@@ -1,4 +1,4 @@
-# 天空盒与一些优化(Sky Box and some optimizations)
+# 天空盒与一些优化 (Sky Box and some optimizations)
 
 ## 天空盒