diff --git a/Makefile b/Makefile
index 50bff0c49b896f02fc5e26a1de41fcc51f91b7b9..638848a35f4914aed3d3cb4f3dbf301e884981b7 100644
--- a/Makefile
+++ b/Makefile
@@ -1,9 +1,13 @@
+CXX ?= g++
 
 build:
-	g++ git-commit-hash-vanity.cc -lssl -lcrypto -lpthread -O3 -o git-commit-hash-vanity
+	$(CXX) git-commit-hash-vanity.cc -lssl -lcrypto -lpthread -O3 -o git-commit-hash-vanity
 
 bench:
-	g++ sha1-benchmark.cc -lssl -lcrypto -O3 -o sha1-benchmark
+	$(CXX) sha1-benchmark.cc -lssl -lcrypto -O3 -o sha1-benchmark
 	time ./sha1-benchmark
 
+install: build
+	cp git-commit-hash-vanity /usr/bin/
+	cp vgitcommit /usr/bin/
 
diff --git a/README.md b/README.md
index 460e129dd236f40409b917faed8c2099fc7b6085..3c1d9a6d594bdbe5798124a837af21556760c069 100644
--- a/README.md
+++ b/README.md
@@ -1,8 +1,15 @@
+# Git commit-hash vanity
 
-1. Run `git commit`
-2. Run `git cat-file commit HEAD`
-3. Run `git reset HEAD~1 --soft`. 
-4. Modify the `catfile_text` and `commit_msg` in `main()` , also modify the hash condition `if(unlikely(*(uint16_t *)hashbuf == 0))`. Also search for `+0800` if you need to modify timezone. 
-5. Commit the result. (You should commit exactly the same changes)
+If you want your git-commit hash looks strange, use me! 
+
+## Installation
+
+Download this project and `make install`. 
+
+## Usage
+
+In your own git repo, you just run `vgitcommit 'Update documents. %s'` instead of running `git commit -m 'Update documents'`. 
+
+By default, this tool generates commit-hash with 8 leading-zero. If you want to change this behavior, just modify line 83 of `git-commit-hash-vanity.cc`.