diff --git a/homeassistant/components/mqtt/__init__.py b/homeassistant/components/mqtt/__init__.py
index 7ff32a79142..b403f296bd8 100644
--- a/homeassistant/components/mqtt/__init__.py
+++ b/homeassistant/components/mqtt/__init__.py
@@ -852,7 +852,8 @@ class MqttAvailability(Entity):
         """(Re)Setup."""
         self._availability_topic = config.get(CONF_AVAILABILITY_TOPIC)
         self._availability_qos = config.get(CONF_QOS)
-        self._available = self._availability_topic is None  # type: bool
+        if self._availability_topic is None:
+            self._available = True
         self._payload_available = config.get(CONF_PAYLOAD_AVAILABLE)
         self._payload_not_available = config.get(CONF_PAYLOAD_NOT_AVAILABLE)