diff --git a/lib/extension/homeassistant.ts b/lib/extension/homeassistant.ts
index 1a4d4085..4047d56d 100644
--- a/lib/extension/homeassistant.ts
+++ b/lib/extension/homeassistant.ts
@@ -158,7 +158,7 @@ const NUMERIC_DISCOVERY_LOOKUP: {[s: string]: KeyValue} = {
     eco_temperature: {entity_category: "config", icon: "mdi:thermometer"},
     energy: {device_class: "energy", state_class: "total_increasing"},
     external_temperature_input: {device_class: "temperature", icon: "mdi:thermometer"},
-    external_temperature: {device_class: "temperature", icon: "mdi:thermometer"},
+    external_temperature: {device_class: "temperature", icon: "mdi:thermometer", state_class: "measurement"},
     external_humidity: {device_class: "humidity", icon: "mdi:water-percent"},
     formaldehyd: {state_class: "measurement"},
     flow: {device_class: "volume_flow_rate", state_class: "measurement"},