diff --git a/homeassistant/components/utility_meter/sensor.py b/homeassistant/components/utility_meter/sensor.py
index f6ac3cb4e09..2d6f5a22532 100644
--- a/homeassistant/components/utility_meter/sensor.py
+++ b/homeassistant/components/utility_meter/sensor.py
@@ -283,7 +283,7 @@ class UtilityMeterSensor(RestoreEntity, SensorEntity):
             return
         _LOGGER.debug("Reset utility meter <%s>", self.entity_id)
         self._last_reset = dt_util.utcnow()
-        self._last_period = str(self._state)
+        self._last_period = str(self._state) if self._state else 0
         self._state = 0
         self.async_write_ha_state()