From c677dae9c1b5bca91fabfc271ffa8feb04f910fe Mon Sep 17 00:00:00 2001
From: jan iversen <jancasacondor@gmail.com>
Date: Sun, 3 Sep 2023 17:48:25 +0200
Subject: [PATCH] Modbus switch, allow restore "unknown" (#99533)

---
 homeassistant/components/modbus/base_platform.py | 6 +++++-
 tests/components/modbus/test_switch.py           | 2 +-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/homeassistant/components/modbus/base_platform.py b/homeassistant/components/modbus/base_platform.py
index 7c3fcd78b05..65cfa1b49ba 100644
--- a/homeassistant/components/modbus/base_platform.py
+++ b/homeassistant/components/modbus/base_platform.py
@@ -21,6 +21,7 @@ from homeassistant.const import (
     CONF_SLAVE,
     CONF_STRUCTURE,
     CONF_UNIQUE_ID,
+    STATE_OFF,
     STATE_ON,
 )
 from homeassistant.core import callback
@@ -311,7 +312,10 @@ class BaseSwitch(BasePlatform, ToggleEntity, RestoreEntity):
         """Handle entity which will be added."""
         await self.async_base_added_to_hass()
         if state := await self.async_get_last_state():
-            self._attr_is_on = state.state == STATE_ON
+            if state.state == STATE_ON:
+                self._attr_is_on = True
+            elif state.state == STATE_OFF:
+                self._attr_is_on = False
 
     async def async_turn(self, command: int) -> None:
         """Evaluate switch result."""
diff --git a/tests/components/modbus/test_switch.py b/tests/components/modbus/test_switch.py
index dce4588d606..7a79e19869a 100644
--- a/tests/components/modbus/test_switch.py
+++ b/tests/components/modbus/test_switch.py
@@ -250,7 +250,7 @@ async def test_lazy_error_switch(
 
 @pytest.mark.parametrize(
     "mock_test_state",
-    [(State(ENTITY_ID, STATE_ON),)],
+    [(State(ENTITY_ID, STATE_ON),), (State(ENTITY_ID, STATE_OFF),)],
     indirect=True,
 )
 @pytest.mark.parametrize(