diff --git a/app/build.gradle b/app/build.gradle
index 6c3878d..bee2586 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -8,8 +8,8 @@ android {
         applicationId "unknownmoon.cryforlight"
         minSdkVersion 23
         targetSdkVersion 23
-        versionCode 4
-        versionName "0.2.2"
+        versionCode 5
+        versionName "0.2.3"
     }
     buildTypes {
         release {
diff --git a/app/build/outputs/apk/app-debug-unaligned.apk b/app/build/outputs/apk/app-debug-unaligned.apk
deleted file mode 100644
index a3c3d1b..0000000
Binary files a/app/build/outputs/apk/app-debug-unaligned.apk and /dev/null differ
diff --git a/app/build/outputs/apk/app-debug.apk b/app/build/outputs/apk/app-debug.apk
deleted file mode 100644
index 5fed94e..0000000
Binary files a/app/build/outputs/apk/app-debug.apk and /dev/null differ
diff --git a/app/src/main/java/unknownmoon/cryforlight/LightService.java b/app/src/main/java/unknownmoon/cryforlight/LightService.java
index e6631bf..e3c5511 100644
--- a/app/src/main/java/unknownmoon/cryforlight/LightService.java
+++ b/app/src/main/java/unknownmoon/cryforlight/LightService.java
@@ -34,6 +34,7 @@ public class LightService extends Service {
     private int mPrefSoundLevel;
     private String mPrefSoundFile;
     private int mPrefLightThreshold;
+    private int mPrefLightThresholdMaxValue;
     private float mLastBrightness;
     private Boolean mIsCrying = false;
     private Ringtone mRingtone;
@@ -162,6 +163,7 @@ private void broadcastStopped() {
 
     private void syncPrefs() {
         syncPref("pref_light");
+        syncPref("pref_light_max");
         syncPref("pref_sound_level");
         syncPref("pref_sound_file");
     }
@@ -173,6 +175,9 @@ private void syncPref(String key) {
             case "pref_light":
                 updateLightThreshold(sharedPrefs.getInt(key, mPrefLightThreshold));
                 break;
+            case "pref_light_max":
+                updateLightThresholdMaxValue(Integer.parseInt(sharedPrefs.getString(key, "" + mPrefLightThresholdMaxValue)));
+                break;
             case "pref_sound_level":
                 updateSoundLevel(sharedPrefs.getInt(key, mPrefSoundLevel));
                 break;
@@ -245,6 +250,11 @@ private void updateLightThreshold(int lvl) {
         Log.d(TAG, "light - " + lvl);
     }
 
+    private void updateLightThresholdMaxValue(int max) {
+        mPrefLightThresholdMaxValue = max;
+        updateLightThreshold(Math.min(mPrefLightThreshold, mPrefLightThresholdMaxValue));
+    }
+
     private void shouldWeCry() {
         if (mLastBrightness <= mPrefLightThreshold && !mIsCrying) {
 
diff --git a/app/src/main/java/unknownmoon/cryforlight/SettingsLightFragment.java b/app/src/main/java/unknownmoon/cryforlight/SettingsLightFragment.java
index 9af06d5..7ae6410 100644
--- a/app/src/main/java/unknownmoon/cryforlight/SettingsLightFragment.java
+++ b/app/src/main/java/unknownmoon/cryforlight/SettingsLightFragment.java
@@ -6,6 +6,7 @@
 import android.content.SharedPreferences;
 import android.os.Bundle;
 import android.preference.PreferenceFragment;
+import android.preference.PreferenceManager;
 import android.support.v4.content.LocalBroadcastManager;
 import android.util.Log;
 
@@ -14,7 +15,7 @@
  * A simple {@link Fragment} subclass.
  */
 public class SettingsLightFragment extends PreferenceFragment implements SharedPreferences.OnSharedPreferenceChangeListener {
-
+    public final String TAG = "SettingsLight";
 
     public SettingsLightFragment() {
         // Required empty public constructor
@@ -27,6 +28,15 @@ public void onCreate(Bundle savedInstanceState) {
         addPreferencesFromResource(R.xml.preferences_light);
     }
 
+    @Override
+    public void onStart() {
+        super.onStart();
+
+        // initialise the saved max value.
+        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getContext());
+        int max = Integer.parseInt(sharedPreferences.getString("pref_light_max", "-1"));
+        broadcastConfigMaxChanged(max, "pref_light");
+    }
 
     @Override
     public void onResume() {
@@ -48,13 +58,37 @@ public void onPause() {
     public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
         if (key.equals("pref_light")) {
             // TODO
-            Log.d("Light", String.format("%s: %d", key, sharedPreferences.getInt(key, getResources().getInteger(R.integer.pref_light_def_val))));
+            Log.d(TAG, String.format("%s: %d", key, sharedPreferences.getInt(key, getResources().getInteger(R.integer.pref_light_def_val))));
             broadcastConfigChanged("pref_light");
+        } else if (key.equals("pref_light_max")) {
+            int max = Integer.parseInt(sharedPreferences.getString(key, "-1"));
+
+            Log.d(TAG, String.format("%s: %d", key, max));
+            broadcastConfigMaxChanged(max, "pref_light");
+            broadcastConfigChanged("pref_light_max");
         }
     }
 
+    /**
+     * Send to SliderPreference only
+     *
+     * @param max New max value.
+     * @param key Preference key of target preference.
+     */
+    private void broadcastConfigMaxChanged(int max, String key) {
+        Intent notifyStartedIntent = new Intent("on-slider-max-changed");
+        notifyStartedIntent.putExtra("changedMax", max);
+        notifyStartedIntent.putExtra("key", key);
+        LocalBroadcastManager.getInstance(getContext()).sendBroadcast(notifyStartedIntent);
+    }
+
+    /**
+     * General notification, for example for sending to LightService
+     *
+     * @param key Changed key.
+     */
     private void broadcastConfigChanged(String key) {
-        // Answer the started
+
         Intent notifyStartedIntent = new Intent("on-configuration-changed");
         notifyStartedIntent.putExtra("changedKey", key);
         LocalBroadcastManager.getInstance(getContext()).sendBroadcast(notifyStartedIntent);
diff --git a/app/src/main/java/unknownmoon/cryforlight/SliderPreference.java b/app/src/main/java/unknownmoon/cryforlight/SliderPreference.java
index 9446a8f..08f1001 100644
--- a/app/src/main/java/unknownmoon/cryforlight/SliderPreference.java
+++ b/app/src/main/java/unknownmoon/cryforlight/SliderPreference.java
@@ -1,9 +1,15 @@
 package unknownmoon.cryforlight;
 
+import android.content.BroadcastReceiver;
 import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
 import android.content.res.TypedArray;
 import android.preference.Preference;
+import android.preference.PreferenceManager;
+import android.support.v4.content.LocalBroadcastManager;
 import android.util.AttributeSet;
+import android.util.Log;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.SeekBar;
@@ -12,19 +18,20 @@
 /**
  * Created by jing on 05/06/2016.
  */
-public class SliderPreference extends Preference implements SeekBar.OnSeekBarChangeListener {
-
+public class SliderPreference extends Preference implements SeekBar.OnSeekBarChangeListener, PreferenceManager.OnActivityDestroyListener {
     public static Boolean DISPLAY_HEADER_LABEL = true;
     public static Boolean DISPLAY_HEADER_VALUE = true;
     public static int SLIDER_MAX = 100;
-
+    public final String TAG = "SliderPreference";
     private Boolean mDisplayHeaderLabel;
     private Boolean mDisplayHeaderValue;
     private String mSummary;
     private String mHeaderLabelText;
     private String mHeaderValueFormat;
+    private int DEFAULT_SLIDER_MAX;
     private int mSliderMax;
     private int mSliderValue;
+    private BroadcastReceiver mMessageReceiver;
 
     public SliderPreference(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
         super(context, attrs, defStyleAttr, defStyleRes);
@@ -37,7 +44,28 @@ public SliderPreference(Context context, AttributeSet attrs, int defStyleAttr, i
         mSummary = a.getString(R.styleable.SliderPreference_summary);
         mHeaderLabelText = a.getString(R.styleable.SliderPreference_headerLabelText);
         mHeaderValueFormat = a.getString(R.styleable.SliderPreference_headerValueFormat);
-        mSliderMax = a.getInt(R.styleable.SliderPreference_sliderMaxValue, SLIDER_MAX);
+        DEFAULT_SLIDER_MAX = a.getInt(R.styleable.SliderPreference_sliderMaxValue, SLIDER_MAX);
+        mSliderMax = getPersistedInt(DEFAULT_SLIDER_MAX);
+
+        mMessageReceiver = new BroadcastReceiver() {
+            @Override
+            public void onReceive(Context context, final Intent intent) {
+                String key = intent.getStringExtra("key");
+
+                if (key.equals(getKey())) {
+                    int changedMax = intent.getIntExtra("changedMax", -1);
+                    Log.d(TAG, "changedMax: " + changedMax);
+                    if (changedMax > 0) {
+                        Log.d(TAG, "update slider max: " + mSliderMax);
+                        updateSliderMax(null, changedMax);
+                        persistSlideValue();
+                    }
+                }
+            }
+        };
+
+        LocalBroadcastManager.getInstance(getContext()).registerReceiver(mMessageReceiver,
+                new IntentFilter("on-slider-max-changed"));
 
         a.recycle();
     }
@@ -65,7 +93,7 @@ protected void onBindView(View view) {
 
         if (seekBarView != null) {
 
-            seekBarView.setMax(mSliderMax);
+            updateSliderMax(seekBarView, mSliderMax);
             seekBarView.setProgress(mSliderValue);
 
             seekBarView.setOnSeekBarChangeListener(this);
@@ -112,9 +140,28 @@ protected void onSetInitialValue(boolean restorePersistedValue, Object defaultVa
 
     }
 
-    private void updateHeaderValueText(TextView v, int value) {
-        if (v != null) {
-            v.setText(String.format(mHeaderValueFormat, value));
+    private void updateSliderMax(SeekBar seekBarView, int max) {
+        if (seekBarView == null) {
+            seekBarView = (SeekBar) getView(null, null).findViewById(R.id.pref_seek_bar);
+        }
+
+        mSliderMax = max > 0 ? max : DEFAULT_SLIDER_MAX;
+
+        if (seekBarView != null) {
+            seekBarView.setMax(max);
+            mSliderValue = Math.min(mSliderValue, max);
+            seekBarView.setProgress(mSliderValue);
+        }
+    }
+
+    private void updateHeaderValueText(TextView headerValueView, int value) {
+
+        if (headerValueView == null) {
+            headerValueView = (TextView) getView(null, null).findViewById(R.id.pref_header_value);
+        }
+
+        if (headerValueView != null) {
+            headerValueView.setText(String.format(mHeaderValueFormat, value));
         }
     }
 
@@ -124,13 +171,13 @@ private void updateSlideValue(int newValue) {
 
     private void persistSlideValue() {
         persistInt(mSliderValue);
+        notifyChanged();
     }
 
     @Override
     public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
-        TextView headerValueView = (TextView) getView(null, (ViewGroup) seekBar.getParent()).findViewById(R.id.pref_header_value);
         updateSlideValue(progress);
-        updateHeaderValueText(headerValueView, progress);
+        updateHeaderValueText((TextView) ((ViewGroup) seekBar.getParent()).findViewById(R.id.pref_header_value), progress);
     }
 
     @Override
@@ -140,6 +187,10 @@ public void onStartTrackingTouch(SeekBar seekBar) {
     @Override
     public void onStopTrackingTouch(SeekBar seekBar) {
         persistSlideValue();
-        notifyChanged();
+    }
+
+    @Override
+    public void onActivityDestroy() {
+        LocalBroadcastManager.getInstance(getContext()).unregisterReceiver(mMessageReceiver);
     }
 }
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 4cb7c55..0b38eb5 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -20,4 +20,6 @@
     <string name="pref_sound_file_title">Sound</string>
     <string name="current_brightness_header">Current Info</string>
     <string name="current_brightness_value_format">%1$.2f lx</string>
+    <string name="pref_light_max_title">Max Brightness</string>
+    <string name="pref_light_max_summary">The max value of the brightness setting.</string>
 </resources>
diff --git a/app/src/main/res/xml/preferences_light.xml b/app/src/main/res/xml/preferences_light.xml
index e005fda..c9b112a 100644
--- a/app/src/main/res/xml/preferences_light.xml
+++ b/app/src/main/res/xml/preferences_light.xml
@@ -6,6 +6,14 @@
         android:key="light_threshold"
         android:title="@string/pref_cat_light">
 
+        <EditTextPreference
+            android:defaultValue="@integer/pref_light_def_max_val"
+            android:key="pref_light_max"
+            android:title="@string/pref_light_max_title"
+            android:summary="@string/pref_light_max_summary"
+            android:inputType="number"
+            />
+
         <unknownmoon.cryforlight.SliderPreference
             android:defaultValue="@integer/pref_light_def_val"
             android:key="pref_light"