diff --git a/src/data/logbook.ts b/src/data/logbook.ts
index 37fa183b75..6509cc5d06 100644
--- a/src/data/logbook.ts
+++ b/src/data/logbook.ts
@@ -10,7 +10,7 @@ import { computeStateDomain } from "../common/entity/compute_state_domain";
 import { LocalizeFunc } from "../common/translations/localize";
 import { HaEntityPickerEntityFilterFunc } from "../components/entity/ha-entity-picker";
 import { HomeAssistant } from "../types";
-import { UNAVAILABLE_STATES } from "./entity";
+import { UNAVAILABLE, UNKNOWN } from "./entity";
 
 const LOGBOOK_LOCALIZE_PATH = "ui.components.logbook.messages";
 export const CONTINUOUS_DOMAINS = ["counter", "proximity", "sensor", "zone"];
@@ -421,7 +421,11 @@ export const localizeStateMessage = (
     return localize(`${LOGBOOK_LOCALIZE_PATH}.turned_off`);
   }
 
-  if (UNAVAILABLE_STATES.includes(state)) {
+  if (state === UNKNOWN) {
+    return localize(`${LOGBOOK_LOCALIZE_PATH}.became_unknown`);
+  }
+
+  if (state === UNAVAILABLE) {
     return localize(`${LOGBOOK_LOCALIZE_PATH}.became_unavailable`);
   }
 
diff --git a/src/translations/en.json b/src/translations/en.json
index 5833a0c573..f08f659a2d 100755
--- a/src/translations/en.json
+++ b/src/translations/en.json
@@ -391,6 +391,7 @@
           "turned_on": "turned on",
           "changed_to_state": "changed to {state}",
           "became_unavailable": "became unavailable",
+          "became_unknown": "became unknown",
           "detected_tampering": "detected tampering",
           "cleared_tampering": "cleared tampering"
         }