diff --git a/android/build.gradle b/android/build.gradle
index 2cf230b..f0828bb 100644
--- a/android/build.gradle
+++ b/android/build.gradle
@@ -2,15 +2,14 @@ group 'com.flutter.moum.screenshot_callback'
 version '1.0'
 
 buildscript {
-    ext.kotlin_version = '1.6.10'
-
+    ext.kotlin_version = '1.7.10'
     repositories {
         google()
         mavenCentral()
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:7.1.2'
+        classpath 'com.android.tools.build:gradle:7.3.0'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }
diff --git a/lib/screenshot_callback.dart b/lib/screenshot_callback.dart
index 77e3ecb..f79f1f5 100644
--- a/lib/screenshot_callback.dart
+++ b/lib/screenshot_callback.dart
@@ -3,16 +3,18 @@ import 'dart:async';
 import 'package:flutter/services.dart';
 
 class ScreenshotCallback {
-  static const MethodChannel _channel =
-      const MethodChannel('flutter.moum/screenshot_callback');
+  static final ScreenshotCallback _singleton = ScreenshotCallback._internal();
+  static ScreenshotCallback get instance => _singleton;
 
-  /// Functions to execute when callback fired.
-  List<VoidCallback> onCallbacks = <VoidCallback>[];
-
-  ScreenshotCallback() {
+  ScreenshotCallback._internal() {
     initialize();
   }
 
+  static const MethodChannel _channel = const MethodChannel('flutter.moum/screenshot_callback');
+
+  /// Functions to execute when callback fired.
+  List<VoidCallback> onCallbacks = <VoidCallback>[];
+
   /// Initializes screenshot callback plugin.
   Future<void> initialize() async {
     _channel.setMethodCallHandler(_handleMethod);
@@ -24,12 +26,20 @@ class ScreenshotCallback {
     onCallbacks.add(callback);
   }
 
+  /// Remove void callback.
+  void removeListener(VoidCallback callback) {
+    onCallbacks.remove(callback);
+  }
+
   Future<dynamic> _handleMethod(MethodCall call) async {
     switch (call.method) {
       case 'onCallback':
-        for (final callback in onCallbacks) {
-          callback();
-        }
+        // for (final callback in onCallbacks) {
+        //   callback();
+        // }
+        // exc last call
+        final callback = onCallbacks.lastOrNull;
+        callback?.call();
         break;
       default:
         throw ('method not defined');