diff --git a/main.py b/main.py
index adca8e2..8bb44ca 100644
--- a/main.py
+++ b/main.py
@@ -1,5 +1,6 @@
 import time
 from machine import Pin, SoftI2C
+import json
 import network
 from simple_mqtt import SimpleMQTT
 
@@ -31,14 +32,12 @@ else:
 # Home Assistant MQTT Discovery
 # -------------------------------------------------------------
 def register_ha_discovery(mqtt, sensor_type):
-    device_info = (
-        f'"device":{{'
-        f'"identifiers":["{Config.NODE_ID}"],'
-        f'"name":"{NODE_NAME}",'
-        f'"model":"Pico 2 W ({sensor_type.upper()})",'
-        f'"manufacturer":"Raspberry Pi"'
-        f"}}"
-    )
+    device_info = {
+        "identifiers": [Config.NODE_ID],
+        "name": NODE_NAME,
+        "model": f"Pico 2 W ({sensor_type.upper()})",
+        "manufacturer": "Raspberry Pi",
+    }
 
     configs = [
         {
@@ -58,31 +57,29 @@ def register_ha_discovery(mqtt, sensor_type):
     ]
 
     if sensor_type == "bme280":
-        configs.append(
-            {
-                "id": "pressure",
-                "name": "Pressure",
-                "unit": "hPa",
-                "cls": "atmospheric_pressure",
-                "val_tpl": "{{ value_json.pressure }}",
-            }
-        )
+        configs.append({
+            "id": "pressure",
+            "name": "Pressure",
+            "unit": "hPa",
+            "cls": "atmospheric_pressure",
+            "val_tpl": "{{ value_json.pressure }}",
+        })
 
     for c in configs:
         topic = f"homeassistant/sensor/{Config.NODE_ID}/{c['id']}/config"
-        unique_id = f"{Config.NODE_ID}_{c['id']}"
-        payload = (
-            f'{{"name":"{c["name"]}",'
-            f'"has_entity_name":true,'
-            f'"unique_id":"{unique_id}",'
-            f'"device_class":"{c["cls"]}",'
-            f'"state_class":"measurement",'
-            f'"unit_of_measurement":"{c["unit"]}",'
-            f'"state_topic":"{STATE_TOPIC}",'
-            f'"value_template":"{c["val_tpl"]}",'
-            f"{device_info}}}"
-        )
-        mqtt.publish(topic, payload, retain=True)
+        payload = {
+            "name": c["name"],
+            "has_entity_name": True,
+            "unique_id": f"{Config.NODE_ID}_{c['id']}",
+            "device_class": c["cls"],
+            "state_class": "measurement",
+            "unit_of_measurement": c["unit"],
+            "state_topic": STATE_TOPIC,
+            "value_template": c["val_tpl"],
+            "device": device_info,
+        }
+
+        mqtt.publish(topic, json.dumps(payload), retain=True)
         print(f"Registered HA discovery: {c['id']}")
 
 
@@ -148,17 +145,8 @@ def main():
         try:
             data = sensor.read_values()
 
-            if data.get("pressure") is not None:
-                state_json = (
-                    f'{{"temperature":{data["temperature"]},'
-                    f'"humidity":{data["humidity"]},'
-                    f'"pressure":{data["pressure"]}}}'
-                )
-            else:
-                state_json = (
-                    f'{{"temperature":{data["temperature"]},'
-                    f'"humidity":{data["humidity"]}}}'
-                )
+            payload = {k: v for k, v in data.items() if v is not None}
+            state_json = json.dumps(payload)
 
             mqtt.publish(STATE_TOPIC, state_json)
             print(f"[{NODE_NAME}] Published: {state_json}")