diff --git a/README.md b/README.md
index 0ae9e62..ba01ee5 100644
--- a/README.md
+++ b/README.md
@@ -20,10 +20,10 @@ The configuration file is a JSON with the following content:
 {
     "mqtt_host": "localhost",
     "mqtt_port": 1883,
-    "dev_id": "my-lumi-router",
     "mqtt_user": "",
     "mqtt_password": "",
-    "topic_root": "lumi/{dev_id}",
+    "device_id": "my-lumi-router",
+    "topic_root": "lumi/{device_id}",
     "sensor_retain": false,
     "sensor_threshold": 50,
     "sensor_debounce_period": 60
@@ -32,7 +32,8 @@ The configuration file is a JSON with the following content:
 Every line is optional. By default, LumiMQTT will use the connection
 to localhost with the anonymous login.
 
-`{dev_id}` **if not provided** will be automatically replaced by a hex number representing a MAC address.
+`device_id` **if not provided** will be automatically replaced by a hex number 
+representing a MAC address of the first network interface.
 
 `sensor_retain` is option to enable storing last sensor value on the broker
 
diff --git a/lumimqtt.json.sample b/lumimqtt.json.sample
index e87f168..714c327 100644
--- a/lumimqtt.json.sample
+++ b/lumimqtt.json.sample
@@ -1,6 +1,6 @@
 {
     "mqtt_host": "localhost",
-    "dev_id": "my-lumi-router",
+    "device_id": "my-lumi-router",
     "mqtt_user": "",
     "mqtt_password": ""
 }
diff --git a/lumimqtt/__main__.py b/lumimqtt/__main__.py
index 7406456..c5698f7 100644
--- a/lumimqtt/__main__.py
+++ b/lumimqtt/__main__.py
@@ -42,10 +42,10 @@ def main():
         except FileNotFoundError:
             pass
 
-    dev_id = read_mac()
+    device_id = read_mac()
     config = {
-        'dev_id': dev_id,
-        'topic_root': 'lumi/{dev_id}',
+        'device_id': device_id,
+        'topic_root': 'lumi/{device_id}',
         'mqtt_host': 'localhost',
         'mqtt_port': 1883,
         'sensor_threshold': 50,  # 5% of illuminance sensor
@@ -53,11 +53,15 @@ def main():
         **config,
     }
 
+    topic_root = \
+        config['topic_root'].\
+        replace('{device_id}', device_id).\
+        replace('{MAC}', device_id)  # support old configs
     server = LumiMqtt(
         reconnection_interval=10,
         loop=loop,
-        dev_id=config['dev_id'],
-        topic_root=config['topic_root'].replace('{dev_id}', dev_id),
+        device_id=config['device_id'],
+        topic_root=topic_root,
         host=config['mqtt_host'],
         port=config['mqtt_port'],
         user=config.get('mqtt_user'),
diff --git a/lumimqtt/lumimqtt.py b/lumimqtt/lumimqtt.py
index 626832c..2877287 100644
--- a/lumimqtt/lumimqtt.py
+++ b/lumimqtt/lumimqtt.py
@@ -29,7 +29,7 @@ class DebounceSensor:
 class LumiMqtt:
     def __init__(
             self,
-            dev_id: str,
+            device_id: str,
             topic_root: str,
             host: str,
             port: int = None,
@@ -42,7 +42,7 @@ def __init__(
             sensor_debounce_period: int,
             loop: ty.Optional[aio.AbstractEventLoop] = None,
     ) -> None:
-        self.dev_id = dev_id
+        self.dev_id = device_id
         self._topic_root = topic_root
         self._topic_lwt = f'{topic_root}/status'
         self._mqtt_host = host