diff --git a/custom_components/hive_local_thermostat/button.py b/custom_components/hive_local_thermostat/button.py
index c365404..28d2854 100644
--- a/custom_components/hive_local_thermostat/button.py
+++ b/custom_components/hive_local_thermostat/button.py
@@ -26,7 +26,7 @@
 from .entity import HiveEntity, HiveEntityDescription
 
 
-@dataclass
+@dataclass(frozen=True, kw_only=True)
 class HiveButtonEntityDescription(
     HiveEntityDescription,
     ButtonEntityDescription,
@@ -66,8 +66,6 @@ async def async_setup_entry(
             )
         )
 
-    _entities = {}
-
     _entities = [
         HiveButton(
             entity_description=entity_description,
diff --git a/custom_components/hive_local_thermostat/climate.py b/custom_components/hive_local_thermostat/climate.py
index 330897a..d374020 100644
--- a/custom_components/hive_local_thermostat/climate.py
+++ b/custom_components/hive_local_thermostat/climate.py
@@ -43,7 +43,7 @@
 }
 
 
-@dataclass
+@dataclass(frozen=True, kw_only=True)
 class HiveClimateEntityDescription(
     HiveEntityDescription,
     ClimateEntityDescription,
@@ -58,8 +58,6 @@ async def async_setup_entry(
 ):
     """Set up the sensor platform."""
 
-    _entities = {}
-
     hive_climate_entity_description = HiveClimateEntityDescription(
         key="climate",
         translation_key="climate",
diff --git a/custom_components/hive_local_thermostat/entity.py b/custom_components/hive_local_thermostat/entity.py
index 758bcdb..7f12532 100644
--- a/custom_components/hive_local_thermostat/entity.py
+++ b/custom_components/hive_local_thermostat/entity.py
@@ -10,14 +10,14 @@
 from .const import DOMAIN
 
 
-@dataclass
+@dataclass(frozen=True, kw_only=True)
 class HiveEntityDescription(EntityDescription):
     """Defines a base Hive entity description."""
 
     entity_id: str | None = None
-    topic: str | None = None
+    topic: str
     entry_id: str | None = None
-    icons_by_state: dict | None = None
+    icons_by_state: dict[str, str] | None = None
     model: str | None = None
 
 class HiveEntity(Entity):
diff --git a/custom_components/hive_local_thermostat/number.py b/custom_components/hive_local_thermostat/number.py
index 59b4afc..3e53b8e 100644
--- a/custom_components/hive_local_thermostat/number.py
+++ b/custom_components/hive_local_thermostat/number.py
@@ -23,6 +23,7 @@
 
 from .const import (
     CONF_MODEL,
+    CONF_MQTT_TOPIC,
     DEFAULT_FROST_TEMPERATURE,
     DEFAULT_HEATING_BOOST_MINUTES,
     DEFAULT_HEATING_BOOST_TEMPERATURE,
@@ -35,7 +36,7 @@
 from .entity import HiveEntity, HiveEntityDescription
 
 
-@dataclass
+@dataclass(frozen=True, kw_only=True)
 class HiveNumberEntityDescription(
     HiveEntityDescription,
     NumberEntityDescription,
@@ -58,7 +59,7 @@ async def async_setup_entry(
             translation_key="heating_boost_duration",
             name=config_entry.title,
             icon="mdi:timer",
-            topic=None,
+            topic=config_entry.options[CONF_MQTT_TOPIC],
             entity_category=EntityCategory.CONFIG,
             native_min_value=30,
             native_max_value=180,
@@ -72,7 +73,7 @@ async def async_setup_entry(
             translation_key="heating_frost_prevention",
             name=config_entry.title,
             icon="mdi:snowflake-thermometer",
-            topic=None,
+            topic=config_entry.options[CONF_MQTT_TOPIC],
             entity_category=EntityCategory.CONFIG,
             device_class=NumberDeviceClass.TEMPERATURE,
             native_unit_of_measurement=UnitOfTemperature.CELSIUS,
@@ -88,7 +89,7 @@ async def async_setup_entry(
             translation_key="heating_default_temperature",
             name=config_entry.title,
             icon="mdi:thermometer",
-            topic=None,
+            topic=config_entry.options[CONF_MQTT_TOPIC],
             entity_category=EntityCategory.CONFIG,
             device_class=NumberDeviceClass.TEMPERATURE,
             native_unit_of_measurement=UnitOfTemperature.CELSIUS,
@@ -104,7 +105,7 @@ async def async_setup_entry(
             translation_key="heating_boost_temperature",
             name=config_entry.title,
             icon="mdi:thermometer",
-            topic=None,
+            topic=config_entry.options[CONF_MQTT_TOPIC],
             entity_category=EntityCategory.CONFIG,
             device_class=NumberDeviceClass.TEMPERATURE,
             native_unit_of_measurement=UnitOfTemperature.CELSIUS,
@@ -124,7 +125,7 @@ async def async_setup_entry(
                 translation_key="water_boost_duration",
                 name=config_entry.title,
                 icon="mdi:timer",
-                topic=None,
+                topic=config_entry.options[CONF_MQTT_TOPIC],
                 entity_category=EntityCategory.CONFIG,
                 native_min_value=30,
                 native_max_value=180,
@@ -135,8 +136,6 @@ async def async_setup_entry(
             )
         )
 
-    _entities = {}
-
     _entities = [
         HiveNumber(
             entity_description=entity_description,
diff --git a/custom_components/hive_local_thermostat/select.py b/custom_components/hive_local_thermostat/select.py
index 730d409..5149095 100644
--- a/custom_components/hive_local_thermostat/select.py
+++ b/custom_components/hive_local_thermostat/select.py
@@ -26,7 +26,7 @@
 from .entity import HiveEntity, HiveEntityDescription
 
 
-@dataclass
+@dataclass(frozen=True, kw_only=True)
 class HiveSelectEntityDescription(
     HiveEntityDescription,
     SelectEntityDescription,
@@ -57,8 +57,6 @@ async def async_setup_entry(
         ),
     )
 
-    _entities = {}
-
     _entities = [HiveSelect(entity_description=entity_description,) for entity_description in ENTITY_DESCRIPTIONS]
 
     async_add_entities(
diff --git a/custom_components/hive_local_thermostat/sensor.py b/custom_components/hive_local_thermostat/sensor.py
index 58f0894..65bf60f 100644
--- a/custom_components/hive_local_thermostat/sensor.py
+++ b/custom_components/hive_local_thermostat/sensor.py
@@ -29,7 +29,7 @@
 from .entity import HiveEntity, HiveEntityDescription
 
 
-@dataclass
+@dataclass(frozen=True, kw_only=True)
 class HiveSensorEntityDescription(
     HiveEntityDescription,
     SensorEntityDescription,
@@ -130,8 +130,6 @@ async def async_setup_entry(
             ),
         ]
 
-    _entities = {}
-
     _entities = [
         HiveSensor(
             entity_description=entity_description,