diff --git a/bundles/org.openhab.io.homekit/src/main/java/org/openhab/io/homekit/internal/accessories/HomekitCharacteristicFactory.java b/bundles/org.openhab.io.homekit/src/main/java/org/openhab/io/homekit/internal/accessories/HomekitCharacteristicFactory.java
index a7a9de2aa..436761182 100644
--- a/bundles/org.openhab.io.homekit/src/main/java/org/openhab/io/homekit/internal/accessories/HomekitCharacteristicFactory.java
+++ b/bundles/org.openhab.io.homekit/src/main/java/org/openhab/io/homekit/internal/accessories/HomekitCharacteristicFactory.java
@@ -262,7 +262,7 @@ public class HomekitCharacteristicFactory {
     }
 
     public static @Nullable Double stateAsTemperature(@Nullable State state) {
-        if (state == null) {
+        if (state == null || state instanceof UnDefType) {
             return null;
         }