diff --git a/README.md b/README.md
index 7e1cc44..9f5fbb1 100644
--- a/README.md
+++ b/README.md
@@ -78,6 +78,8 @@ Environment variables (will overwrite other server configs)
 | variables | example values | description |
 | --------- | ------ | ----------- |
 | NODE_ENV  | `production` or `development` | set current environment (will apply correspond settings in the `config.json`) |
+| DOMAIN | `hackmd.io` | domain name |
+| URL_PATH | `hackmd` | sub url path, like `www.example.com/<URL_PATH>` |
 | PORT | `80` | web app port |
 | DEBUG | `true` or `false` | set debug mode, show more logs |
 
diff --git a/lib/config.js b/lib/config.js
index 386b088..7028f29 100644
--- a/lib/config.js
+++ b/lib/config.js
@@ -7,8 +7,8 @@ var config = require(path.join(__dirname, '..', 'config.json'))[env];
 var debug = process.env.DEBUG ? (process.env.DEBUG === 'true') : ((typeof config.debug === 'boolean') ? config.debug : (env === 'development'));
 
 // url
-var domain = config.domain || 'localhost';
-var urlpath = config.urlpath || '';
+var domain = process.env.DOMAIN || config.domain || '';
+var urlpath = process.env.URL_PATH || config.urlpath || '';
 var port = process.env.PORT || config.port || 3000;
 var alloworigin = config.alloworigin || ['localhost'];