diff --git a/docs/操作系统/CS162.en.md b/docs/操作系统/CS162.en.md
index 0c793257..c9f4fe90 100644
--- a/docs/操作系统/CS162.en.md
+++ b/docs/操作系统/CS162.en.md
@@ -5,7 +5,7 @@
 - Offered by: UC Berkeley
 - Prerequisites: CS61A, CS61B, CS61C
 - Programming Languages: C, x86 Assembly
-- Difficulty：🌟🌟🌟🌟🌟🌟
+- Difficulty: 🌟🌟🌟🌟🌟🌟
 - Class Hour: 200 hours+
 
 The course impressed me in two aspects: