diff --git a/homeassistant/components/trend/binary_sensor.py b/homeassistant/components/trend/binary_sensor.py
index fe3d10ab72c..2b1ae0e083a 100644
--- a/homeassistant/components/trend/binary_sensor.py
+++ b/homeassistant/components/trend/binary_sensor.py
@@ -10,7 +10,7 @@ from homeassistant.components.binary_sensor import (
     BinarySensorDevice)
 from homeassistant.const import (
     ATTR_ENTITY_ID, ATTR_FRIENDLY_NAME, CONF_DEVICE_CLASS, CONF_ENTITY_ID,
-    CONF_FRIENDLY_NAME, STATE_UNKNOWN, CONF_SENSORS)
+    CONF_FRIENDLY_NAME, STATE_UNKNOWN, STATE_UNAVAILABLE, CONF_SENSORS)
 from homeassistant.core import callback
 import homeassistant.helpers.config_validation as cv
 from homeassistant.helpers.entity import generate_entity_id
@@ -140,7 +140,7 @@ class SensorTrend(BinarySensorDevice):
                     state = new_state.attributes.get(self._attribute)
                 else:
                     state = new_state.state
-                if state != STATE_UNKNOWN:
+                if state not in (STATE_UNKNOWN, STATE_UNAVAILABLE):
                     sample = (utcnow().timestamp(), float(state))
                     self.samples.append(sample)
                     self.async_schedule_update_ha_state(True)