From 2c451e6a76198bfd95ea2d05b25270bd6a973980 Mon Sep 17 00:00:00 2001
From: Paulus Schoutsen <balloob@gmail.com>
Date: Tue, 7 Dec 2021 22:38:35 -0800
Subject: [PATCH] Fix litterrobot timestamp sensor (#61208)

* Fix litterrobot timestamp sensor

* Update type
---
 homeassistant/components/litterrobot/sensor.py | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/homeassistant/components/litterrobot/sensor.py b/homeassistant/components/litterrobot/sensor.py
index 1fab6983249..6b4dc1b3300 100644
--- a/homeassistant/components/litterrobot/sensor.py
+++ b/homeassistant/components/litterrobot/sensor.py
@@ -1,9 +1,11 @@
 """Support for Litter-Robot sensors."""
 from __future__ import annotations
 
+from datetime import datetime
+
 from pylitterbot.robot import Robot
 
-from homeassistant.components.sensor import SensorEntity
+from homeassistant.components.sensor import SensorEntity, StateType
 from homeassistant.config_entries import ConfigEntry
 from homeassistant.const import DEVICE_CLASS_TIMESTAMP, PERCENTAGE
 from homeassistant.core import HomeAssistant
@@ -36,7 +38,7 @@ class LitterRobotPropertySensor(LitterRobotEntity, SensorEntity):
         self.sensor_attribute = sensor_attribute
 
     @property
-    def native_value(self) -> str:
+    def native_value(self) -> StateType | datetime:
         """Return the state."""
         return getattr(self.robot, self.sensor_attribute)
 
@@ -59,10 +61,10 @@ class LitterRobotSleepTimeSensor(LitterRobotPropertySensor):
     """Litter-Robot sleep time sensor."""
 
     @property
-    def native_value(self) -> str | None:
+    def native_value(self) -> StateType | datetime:
         """Return the state."""
         if self.robot.sleep_mode_enabled:
-            return super().native_value.isoformat()
+            return super().native_value
         return None
 
     @property