diff --git a/doc/README.md b/doc/README.md
index 7956829..68bca97 100644
--- a/doc/README.md
+++ b/doc/README.md
@@ -38,4 +38,14 @@ or
 
 ![alt text](./assets/start_node_server2.png)
 
-the second method uses the [nodemon.json](../nodemon.json) to configure nodemon.
\ No newline at end of file
+the second method uses the [nodemon.json](../nodemon.json) to configure nodemon.
+
+# .env file
+
+To have different behavior on your dev host, you cloud add an .env file.
+
+Here are the key-values of an .evc file:
+
+```bash
+PORT = 3000
+```
\ No newline at end of file
diff --git a/src/server.js b/src/server.js
index 0e9c2ca..a25e58d 100644
--- a/src/server.js
+++ b/src/server.js
@@ -33,5 +33,6 @@ app.get('/', (req, res) => {
     res.render('index.ejs')
 })
 
-const port = process.env.PORT;
+const port = process.env.PORT || 3000;;
+
 app.listen(port, () => console.log("Server is running on http://localhost:%i", port));
\ No newline at end of file