diff --git a/custom_components/sonoff/binary_sensor.py b/custom_components/sonoff/binary_sensor.py
index 47bb397..a8c20b3 100644
--- a/custom_components/sonoff/binary_sensor.py
+++ b/custom_components/sonoff/binary_sensor.py
@@ -148,7 +148,12 @@ async def async_added_to_hass(self) -> None:
             and self.timeout
             and (ts := restore.attributes.get(ATTR_LAST_TRIGGERED))
         ):
-            left = self.timeout - (dt.utcnow() - dt.parse_datetime(ts)).seconds
+            triggered_at = dt.parse_datetime(ts)
+            if triggered_at is None:
+                self._attr_is_on = False
+                return
+
+            left = self.timeout - (dt.utcnow() - triggered_at).total_seconds()
             if left > 0:
                 self.task = asyncio.create_task(self.clear_state(left))
             else:
diff --git a/tests/test_entity.py b/tests/test_entity.py
index a2da75a..6bdd31b 100644
--- a/tests/test_entity.py
+++ b/tests/test_entity.py
@@ -10,14 +10,17 @@
 )
 from homeassistant.components.sensor import SensorDeviceClass, SensorStateClass
 from homeassistant.components.switch import SwitchEntity
+from homeassistant.components.script import ATTR_LAST_TRIGGERED
 from homeassistant.const import (
     CONCENTRATION_PARTS_PER_MILLION,
     MAJOR_VERSION,
     MINOR_VERSION,
+    STATE_ON,
     UnitOfEnergy,
     UnitOfVolume,
 )
 from homeassistant.helpers.device_registry import CONNECTION_NETWORK_MAC
+from homeassistant.util import dt
 
 from custom_components.sonoff import CONFIG_SCHEMA, remote
 from custom_components.sonoff.binary_sensor import XBinarySensor, XRemoteSensor
@@ -70,6 +73,8 @@
 )
 from . import DEVICEID, DummyRegistry, init, save_to
 
+from datetime import timedelta
+from types import SimpleNamespace
 
 def get_entitites(device: Union[dict, list], config: dict = None) -> list:
     return init(device, config)[1]
@@ -678,6 +683,29 @@ def test_rfbridge_button_override_without_timeout():
     assert button.name == "Button A"
 
 
+def test_remote_sensor_restore_uses_total_seconds():
+    sensor = XRemoteSensor(
+        DummyRegistry(),
+        {"deviceid": DEVICEID},
+        {"channel": "0", "name": "Button", "timeout": 120},
+    )
+
+    old_trigger = (dt.utcnow() - timedelta(days=1, seconds=30)).isoformat()
+
+    async def async_get_last_state():
+        return SimpleNamespace(
+            state=STATE_ON,
+            attributes={ATTR_LAST_TRIGGERED: old_trigger},
+        )
+
+    sensor.async_get_last_state = async_get_last_state
+
+    await_(sensor.async_added_to_hass())
+
+    assert sensor.is_on is False
+    assert sensor.task is None
+
+
 def test_wifi_sensor():
     entities = get_entitites(
         {