diff --git a/homeassistant/components/geonetnz_volcano/sensor.py b/homeassistant/components/geonetnz_volcano/sensor.py
index 583b75a24eb..f02e076b66c 100644
--- a/homeassistant/components/geonetnz_volcano/sensor.py
+++ b/homeassistant/components/geonetnz_volcano/sensor.py
@@ -63,6 +63,7 @@ class GeonetnzVolcanoSensor(SensorEntity):
         self._config_entry_id = config_entry_id
         self._feed_manager = feed_manager
         self._external_id = external_id
+        self._attr_unique_id = f"{config_entry_id}_{external_id}"
         self._unit_system = unit_system
         self._title = None
         self._distance = None