diff --git a/aircon/__main__.py b/aircon/__main__.py
index 51fe5a2..f0b4aad 100644
--- a/aircon/__main__.py
+++ b/aircon/__main__.py
@@ -209,6 +209,14 @@ async def run(parsed_args):
               'name': device.name,
               'sw_version': device.sw_version
           },
+          'availability': [
+              {
+                  'topic': mqtt_topics['lwt']
+              },
+              {
+                  'topic': mqtt_topics['pub'].format(device.mac_address, 'available')
+              },
+          ],
           'current_temperature_topic': mqtt_topics['pub'].format(device.mac_address, 'f_temp_in'),
           'fan_mode_command_topic': mqtt_topics['sub'].format(device.mac_address, 't_fan_speed'),
           'fan_mode_state_topic': mqtt_topics['pub'].format(device.mac_address, 't_fan_speed'),
diff --git a/aircon/aircon.py b/aircon/aircon.py
index 96f7c51..91b09b8 100644
--- a/aircon/aircon.py
+++ b/aircon/aircon.py
@@ -33,6 +33,7 @@ def __init__(self, config: Dict[str, str], properties: Properties, notifier: Cal
     self._properties = properties
     self._properties_lock = threading.RLock()
     self._queue_listener = notifier
+    self._available = False
 
     self._next_command_id = 0
 
@@ -49,6 +50,15 @@ def __init__(self, config: Dict[str, str], properties: Properties, notifier: Cal
   def is_fahrenheit(self) -> bool:
     return self.temp_type == TemperatureUnit.FAHRENHEIT
 
+  @property
+  def available(self) -> bool:
+    return self._available
+
+  @available.setter
+  def available(self, value: bool):
+    self._available = value
+    self._notify_listeners('available', 'online' if value else 'offline')
+
   def add_property_change_listener(self, listener: Callable[[str, Any], None]):
     self._property_change_listeners.append(listener)
 
@@ -183,15 +193,6 @@ class AcDevice(BaseDevice):
   def __init__(self, config: Dict[str, str], notifier: Callable[[None], None]):
     super().__init__(config, AcProperties(), notifier)
 
-  @property
-  def available(self) -> bool:
-    return self._available
-
-  @available.setter
-  def available(self, value: bool):
-    self._available = value
-    self._notify_listeners("available", value)
-
   # @override to add special support for t_power.
   def update_property(self, name: str, value) -> None:
     with self._properties_lock:
diff --git a/aircon/notifier.py b/aircon/notifier.py
index 2fdcce0..9ac8a84 100644
--- a/aircon/notifier.py
+++ b/aircon/notifier.py
@@ -23,7 +23,6 @@
 class _NotifyConfiguration:
   device: BaseDevice
   headers: dict
-  alive: bool
   last_timestamp: int
 
 
@@ -60,7 +59,7 @@ def register_device(self, device: BaseDevice):
           'Host': device.ip_address,
           'Accept-Encoding': 'gzip'
       }
-      self._configurations.append(_NotifyConfiguration(device, headers, False, 0))
+      self._configurations.append(_NotifyConfiguration(device, headers, 0))
 
   async def _notify(self):
     async with self._condition:
@@ -75,17 +74,20 @@ async def start(self, session: aiohttp.ClientSession):
     async with self._condition:
       while self._running:
         queues_empty = True
-        for entry in self._configurations:
+        for config in self._configurations:
           try:
             now = time.time()
-            queue_size = entry.device.commands_queue.qsize()
+            queue_size = config.device.commands_queue.qsize()
             if queue_size > 1:
               queues_empty = False
-            if now - entry.last_timestamp >= self._KEEP_ALIVE_INTERVAL or queue_size > 0:
-              await self._perform_request(session, entry)
-              entry.last_timestamp = now
+            if now - config.last_timestamp >= self._KEEP_ALIVE_INTERVAL or queue_size > 0:
+              await self._perform_request(session, config)
+              config.last_timestamp = now
           except:
             logging.exception('[KeepAlive] Failed to send local_reg keep alive to the AC.')
+            config.device.available = False
+          else:
+            config.device.available = True
         if queues_empty:
           logging.debug('[KeepAlive] Waiting for notification or timeout')
           try:
@@ -104,7 +106,7 @@ async def stop(self):
          wait=wait_incrementing(start=0.5, increment=1.5, max=10))
   async def _perform_request(self, session: aiohttp.ClientSession,
                              config: _NotifyConfiguration) -> None:
-    method = 'PUT' if config.alive else 'POST'
+    method = 'PUT' if config.device.available else 'POST'
     self._json['local_reg']['notify'] = int(config.device.commands_queue.qsize() > 0)
     url = 'http://{}/local_reg.json'.format(config.device.ip_address)
     try:
@@ -116,6 +118,7 @@ async def _perform_request(self, session: aiohttp.ClientSession,
               resp.status, resp_data))
           raise ConnectionError('Sending local_reg failed: {}, {}'.format(resp.status, resp_data))
     except:
-      config.alive = False
+      config.device.available = False
       raise
-    config.alive = True
+    else:
+      config.device.available = True