diff --git a/README.md b/README.md
index 4484632..c1336d1 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,7 @@ Step 5: Start ngrok service by typing:
 or just execute `install.sh` on Linux x64 platform.
 
 ```
+    curl -O https://raw.githubusercontent.com/vincenthsu/systemd-ngrok/master/install.sh
     chmod +x install.sh
-    ./install.sh <your_authtoken>
+    sudo ./install.sh <your_authtoken>
 ```
diff --git a/install.sh b/install.sh
index 9069711..f9ea057 100755
--- a/install.sh
+++ b/install.sh
@@ -10,8 +10,10 @@ if [ -z "$1" ]; then
     exit 1
 fi
 
-git clone https://github.com/vincenthsu/systemd-ngrok.git
-cd systemd-ngrok
+if [ ! -e ngrok.service ]; then
+    git clone --depth=1 https://github.com/vincenthsu/systemd-ngrok.git
+    cd systemd-ngrok
+fi
 cp ngrok.service /lib/systemd/system/
 mkdir -p /opt/ngrok
 cp ngrok.yml /opt/ngrok
@@ -20,7 +22,7 @@ sed -i "s/<add_your_token_here>/$1/g" /opt/ngrok/ngrok.yml
 cd /opt/ngrok
 wget https://bin.equinox.io/c/4VmDzA7iaHb/ngrok-stable-linux-amd64.zip
 unzip ngrok-stable-linux-amd64.zip
-
+rm ngrok-stable-linux-amd64.zip
 chmod +x ngrok
 
 systemctl enable ngrok.service