diff --git a/.prettierignore b/.prettierignore
new file mode 100644
index 0000000..b43bf86
--- /dev/null
+++ b/.prettierignore
@@ -0,0 +1 @@
+README.md
diff --git a/README.md b/README.md
index a571d19..59e2074 100644
--- a/README.md
+++ b/README.md
@@ -124,6 +124,11 @@ For development or custom modifications:
 The application can be configured using either command-line arguments or environment variables. Environment variables
 take precedence over command-line defaults.
 
+> [!IMPORTANT]
+> The `M2M_TEMPERATURE_UNIT` option must match Home Assistant's unit system (Settings → General → Unit System)
+> so setpoints and readings are interpreted correctly. If mismatched, climate entities will show incorrect values (e.g.
+> 21°C treated as 21°F) and commands may result in unexpected temperatures.
+
 ### Required Configuration
 
 | CLI Option            | Environment Variable | Description                      |
@@ -151,6 +156,7 @@ take precedence over command-line defaults.
 | `-l, --log-level`         | `M2M_LOG_LEVEL`         | `info`         | Log level: `silent`, `fatal`, `error`, `warn`, `info`, `debug`, `trace` |
 | `-f, --log-format`        | `M2M_LOG_FORMAT`        | `pretty`       | Log format: `pretty`, `json`                                            |
 | `-s, --mysa-session-file` | `M2M_MYSA_SESSION_FILE` | `session.json` | Path to Mysa session file                                               |
+| `-t, --temperature-unit`  | `M2M_TEMPERATURE_UNIT`  | `C`            | Temperature unit (`C` = Celsius, `F` = Fahrenheit)                      |
 
 ## Usage Examples
 
diff --git a/src/main.ts b/src/main.ts
index 6e48a23..7ce5d35 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -99,7 +99,8 @@ async function main() {
         mqttSettings,
         new PinoLogger(rootLogger.child({ module: 'thermostat', deviceId: device.Id })),
         firmwares.Firmware[device.Id],
-        serialNumbers.get(device.Id)
+        serialNumbers.get(device.Id),
+        options.temperatureUnit
       )
   );
 
diff --git a/src/options.ts b/src/options.ts
index af99ec0..4d2439f 100644
--- a/src/options.ts
+++ b/src/options.ts
@@ -143,5 +143,12 @@ export const options = new Command('mysa2mqtt')
       .default('mysa2mqtt')
       .helpGroup('MQTT')
   )
+  .addOption(
+    new Option('--temperature-unit <temperatureUnit>', 'temperature unit (C or F)')
+      .env('M2M_TEMPERATURE_UNIT')
+      .choices(['C', 'F'])
+      .default('C')
+      .helpGroup('Configuration')
+  )
   .parse()
   .opts();
diff --git a/src/thermostat.ts b/src/thermostat.ts
index 496df2d..229ebe2 100644
--- a/src/thermostat.ts
+++ b/src/thermostat.ts
@@ -51,8 +51,11 @@ export class Thermostat {
     private readonly mqttSettings: MqttSettings,
     private readonly logger: Logger,
     public readonly mysaDeviceFirmware?: FirmwareDevice,
-    public readonly mysaDeviceSerialNumber?: string
+    public readonly mysaDeviceSerialNumber?: string,
+    public readonly temperatureUnit?: 'C' | 'F'
   ) {
+    const is_celsius = (temperatureUnit ?? 'C') === 'C';
+
     this.mqttDevice = {
       identifiers: mysaDevice.Id,
       name: mysaDevice.Name,
@@ -81,9 +84,9 @@ export class Thermostat {
           min_temp: mysaDevice.MinSetpoint,
           max_temp: mysaDevice.MaxSetpoint,
           modes: ['off', 'heat'], // TODO: AC
-          precision: 0.1,
-          temp_step: 0.5,
-          temperature_unit: 'C', // TODO: Confirm that Mysa always works in C
+          precision: is_celsius ? 0.1 : 1.0,
+          temp_step: is_celsius ? 0.5 : 1.0,
+          temperature_unit: 'C',
           optimistic: true
         }
       },
@@ -118,7 +121,17 @@ export class Thermostat {
             if (message === '') {
               this.mysaApiClient.setDeviceState(this.mysaDevice.Id, undefined, undefined);
             } else {
-              this.mysaApiClient.setDeviceState(this.mysaDevice.Id, parseFloat(message), undefined);
+              let temperature = parseFloat(message);
+
+              if (!is_celsius) {
+                const snapHalfC = (c: number) => Math.round(c * 2) / 2;
+                const clamp = (v: number, min: number, max: number) => Math.min(max, Math.max(min, v));
+                // Snap to 0.5 °C and clamp to device limits
+                const setC = snapHalfC(temperature);
+                temperature = clamp(setC, this.mysaDevice.MinSetpoint ?? 0, this.mysaDevice.MaxSetpoint ?? 100);
+              }
+
+              this.mysaApiClient.setDeviceState(this.mysaDevice.Id, temperature, undefined);
             }
             break;
         }
@@ -137,7 +150,7 @@ export class Thermostat {
         device_class: 'temperature',
         state_class: 'measurement',
         unit_of_measurement: '°C',
-        suggested_display_precision: 1,
+        suggested_display_precision: is_celsius ? 0.1 : 0.0,
         force_update: true
       }
     });