diff --git a/homeassistant/components/tellduslive/sensor.py b/homeassistant/components/tellduslive/sensor.py
index e588ea6318f..9bd2b1fe599 100644
--- a/homeassistant/components/tellduslive/sensor.py
+++ b/homeassistant/components/tellduslive/sensor.py
@@ -194,4 +194,4 @@ class TelldusLiveSensor(TelldusLiveEntity, SensorEntity):
     @property
     def unique_id(self) -> str:
         """Return a unique ID."""
-        return "-".join(self._id)
+        return "-".join(map(str, self._id))