diff --git a/internal/agent/mqtt.go b/internal/agent/mqtt.go
index 2bcbc9a80..14c7c8204 100644
--- a/internal/agent/mqtt.go
+++ b/internal/agent/mqtt.go
@@ -7,6 +7,7 @@ package agent
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"log/slog"
 
@@ -71,8 +72,10 @@ func setupMQTT(ctx context.Context) []MQTTWorker {
 	// Set up custom MQTT commands worker.
 	customCommandsWorker, err := commands.NewCommandsWorker(ctx, mqttDevice)
 	if err != nil {
-		logging.FromContext(ctx).Warn("Could not setup custom MQTT commands.",
-			slog.Any("error", err))
+		if !errors.Is(err, commands.ErrNoCommands) {
+			logging.FromContext(ctx).Warn("Could not setup custom MQTT commands.",
+				slog.Any("error", err))
+		}
 	} else {
 		workers = append(workers, customCommandsWorker)
 	}
diff --git a/internal/hass/registration.go b/internal/hass/registration.go
index 768cd561d..a59824701 100644
--- a/internal/hass/registration.go
+++ b/internal/hass/registration.go
@@ -53,6 +53,14 @@ func RegisterDevice(ctx context.Context, registration *preferences.Registration)
 	registrationURL := registration.Server + RegistrationPath
 	thisDevice := device.NewDevice()
 
+	// Set device details in preferences.
+	if err := preferences.SetDevicePreferences(&preferences.Device{
+		Name: thisDevice.Name,
+		ID:   thisDevice.ID,
+	}); err != nil {
+		return nil, fmt.Errorf("could not register device: %w", err)
+	}
+
 	// Register the device against the registration endpoint.
 	registrationStatus, err := api.Send[preferences.Hass](ctx, registrationURL, newRegistrationRequest(thisDevice, registration.Token))
 	if err != nil {
diff --git a/internal/preferences/mqtt.go b/internal/preferences/mqtt.go
index 9baa90dec..203adfc6e 100644
--- a/internal/preferences/mqtt.go
+++ b/internal/preferences/mqtt.go
@@ -18,16 +18,16 @@ const (
 	prefMQTTServer      = mqttPrefPrefix + ".server"
 	prefMQTTUser        = mqttPrefPrefix + ".user"
 	prefMQTTPass        = mqttPrefPrefix + ".password"
-	prefMQTTTopicPrefix = mqttPrefPrefix + ".topic_prefx"
+	prefMQTTTopicPrefix = mqttPrefPrefix + ".topic_prefix"
 	prefMQTTEnabled     = mqttPrefPrefix + ".enabled"
 )
 
 // MQTT contains preferences related to MQTT functionality in Go Hass Agent.
 type MQTT struct {
-	MQTTServer      string `toml:"server,omitempty" validate:"omitempty,uri" kong:"required,help='MQTT server URI. Required.',placeholder='scheme://some.host:port'"` //nolint:lll
+	MQTTServer      string `toml:"server,omitempty" validate:"required,uri" kong:"required,help='MQTT server URI. Required.',placeholder='scheme://some.host:port'"` //nolint:lll
 	MQTTUser        string `toml:"user,omitempty" validate:"omitempty" kong:"optional,help='MQTT username.'"`
 	MQTTPassword    string `toml:"password,omitempty" validate:"omitempty" kong:"optional,help='MQTT password.'"`
-	MQTTTopicPrefix string `toml:"topic_prefix,omitempty" validate:"omitempty,ascii" kong:"optional,help='MQTT topic prefix.'"`
+	MQTTTopicPrefix string `toml:"topic_prefix,omitempty" validate:"required,ascii" kong:"optional,help='MQTT topic prefix.'"`
 	MQTTEnabled     bool   `toml:"enabled" validate:"boolean" kong:"-"`
 }
 
@@ -48,6 +48,10 @@ func SetMQTTPreferences(prefs *MQTT) error {
 		return fmt.Errorf("%w: %w", ErrSetMQTTPreference, err)
 	}
 
+	if prefs.MQTTTopicPrefix == "" {
+		prefs.MQTTTopicPrefix = MQTTTopicPrefix
+	}
+
 	if err := prefsSrc.Set(prefMQTTTopicPrefix, prefs.MQTTTopicPrefix); err != nil {
 		return fmt.Errorf("%w: %w", ErrSetMQTTPreference, err)
 	}
diff --git a/internal/preferences/prefs.go b/internal/preferences/prefs.go
index a344b1bc0..8a97fc802 100644
--- a/internal/preferences/prefs.go
+++ b/internal/preferences/prefs.go
@@ -13,7 +13,6 @@ import (
 	"sync"
 
 	"github.com/adrg/xdg"
-	"github.com/davecgh/go-spew/spew"
 	"github.com/knadh/koanf/parsers/toml"
 	"github.com/knadh/koanf/providers/env"
 	"github.com/knadh/koanf/providers/file"
@@ -60,7 +59,8 @@ var defaultAgentPreferences = &preferences{
 	Version:    AppVersion(),
 	Registered: false,
 	MQTT: &MQTT{
-		MQTTEnabled: false,
+		MQTTEnabled:     false,
+		MQTTTopicPrefix: MQTTTopicPrefix,
 	},
 	Registration: &Registration{
 		Server: DefaultServer,
@@ -147,13 +147,24 @@ func validate() error {
 		return fmt.Errorf("%w: %w", ErrLoadPreferences, err)
 	}
 
-	// Validate current preferences.
-	err := validation.Validate.Struct(currentPreferences)
-	if err != nil {
-		spew.Dump(err)
+	// Ensure device preferences are valid.
+	if err := validation.Validate.Struct(currentPreferences.Device); err != nil {
+		return fmt.Errorf("%w: %s", ErrValidatePreferences, validation.ParseValidationErrors(err))
+	}
+
+	// Ensure hass preferences are valid.
+	if err := validation.Validate.Struct(currentPreferences.Hass); err != nil {
 		return fmt.Errorf("%w: %s", ErrValidatePreferences, validation.ParseValidationErrors(err))
 	}
 
+	if currentPreferences.IsMQTTEnabled() {
+		// Validate MQTT preferences are valid.
+		err := validation.Validate.Struct(currentPreferences.MQTT)
+		if err != nil {
+			return fmt.Errorf("%w: %s", ErrValidatePreferences, validation.ParseValidationErrors(err))
+		}
+	}
+
 	slog.Debug("Preferences are valid.")
 
 	return nil