diff --git a/Makefile b/Makefile
index f765bf8..b10da39 100644
--- a/Makefile
+++ b/Makefile
@@ -1,16 +1,10 @@
-include nemu/Makefile.git
+include nemu/scripts/git.mk
 
 default:
 	@echo "Please run 'make' under any subprojects to compile."
 
-clean:
-	-$(MAKE) -s -C nemu clean
-	-$(MAKE) -s -C abstract-machine clean-all
-	-$(MAKE) -s -C nanos-lite clean
-	-$(MAKE) -s -C navy-apps clean
-
-submit: clean
+submit:
 	git gc
 	STUID=$(STUID) STUNAME=$(STUNAME) bash -c "$$(curl -s http://jyywiki.cn/static/submit.sh)"
 
-.PHONY: default clean submit
+.PHONY: default submit
diff --git a/README.md b/README.md
index 9e1b853..c4333b6 100644
--- a/README.md
+++ b/README.md
@@ -1,10 +1,10 @@
-# ICS2020 Programming Assignment
+# ICS2021 Programming Assignment
 
 This project is the programming assignment of the class ICS(Introduction to Computer System)
 in Department of Computer Science and Technology, Nanjing University.
 
 For the guide of this programming assignment,
-refer to http://nju-ics.gitbooks.io/ics2020-programming-assignment/content/
+refer to http://nju-ics.gitbooks.io/ics2021-programming-assignment/content/
 
 To initialize, run
 ```bash
diff --git a/init.sh b/init.sh
index 6931eba..b6a251c 100644
--- a/init.sh
+++ b/init.sh
@@ -1,6 +1,6 @@
 #!/bin/bash
 
-version=ics2020
+version=ics2021
 
 function init() {
   if [ -d $1 ]; then