diff --git a/gradle/versions.gradle b/gradle/versions.gradle
index 1a8f14d4..a37848a0 100644
--- a/gradle/versions.gradle
+++ b/gradle/versions.gradle
@@ -1,5 +1,5 @@
 ext.versions = [
         minSdk               : 21,
-        targetSdk            : 30,
+        targetSdk            : 31,
         compileSdk           : 31,
 ]
\ No newline at end of file
diff --git a/ultrasonic/src/main/AndroidManifest.xml b/ultrasonic/src/main/AndroidManifest.xml
index 27946252..78fc9d0f 100644
--- a/ultrasonic/src/main/AndroidManifest.xml
+++ b/ultrasonic/src/main/AndroidManifest.xml
@@ -40,7 +40,8 @@
 
         <activity android:name=".activity.NavigationActivity"
             android:configChanges="orientation|keyboardHidden"
-            android:launchMode="singleTask">
+            android:launchMode="singleTask"
+            android:exported="true">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <action android:name="android.intent.action.SEARCH"/>
@@ -63,7 +64,7 @@
 
         <service android:name=".playback.PlaybackService"
             android:label="@string/common.appname"
-            android:exported="true">
+            android:exported="false">
 
             <intent-filter>
                 <action android:name="androidx.media3.session.MediaLibraryService" />
@@ -71,7 +72,8 @@
             </intent-filter>
         </service>
 
-        <receiver android:name=".receiver.UltrasonicIntentReceiver">
+        <receiver android:name=".receiver.UltrasonicIntentReceiver"
+            android:exported="false">
             <intent-filter>
                 <action android:name="org.moire.ultrasonic.CMD_TOGGLEPAUSE"/>
                 <action android:name="org.moire.ultrasonic.CMD_PLAY"/>
@@ -85,7 +87,8 @@
         </receiver>
         <receiver
             android:name=".provider.UltrasonicAppWidgetProvider4X1"
-            android:label="Ultrasonic (4x1)">
+            android:label="Ultrasonic (4x1)"
+            android:exported="false">
             <intent-filter>
                 <action android:name="android.appwidget.action.APPWIDGET_UPDATE"/>
             </intent-filter>
@@ -96,7 +99,8 @@
         </receiver>
         <receiver
             android:name=".provider.UltrasonicAppWidgetProvider4X2"
-            android:label="Ultrasonic (4x2)">
+            android:label="Ultrasonic (4x2)"
+            android:exported="false">
             <intent-filter>
                 <action android:name="android.appwidget.action.APPWIDGET_UPDATE"/>
             </intent-filter>
@@ -107,7 +111,8 @@
         </receiver>
         <receiver
             android:name=".provider.UltrasonicAppWidgetProvider4X3"
-            android:label="Ultrasonic (4x3)">
+            android:label="Ultrasonic (4x3)"
+            android:exported="false">
             <intent-filter>
                 <action android:name="android.appwidget.action.APPWIDGET_UPDATE"/>
             </intent-filter>
@@ -118,7 +123,8 @@
         </receiver>
         <receiver
             android:name=".provider.UltrasonicAppWidgetProvider4X4"
-            android:label="Ultrasonic (4x4)">
+            android:label="Ultrasonic (4x4)"
+            android:exported="false">
             <intent-filter>
                 <action android:name="android.appwidget.action.APPWIDGET_UPDATE"/>
             </intent-filter>
@@ -127,14 +133,16 @@
                 android:name="android.appwidget.provider"
                 android:resource="@xml/appwidget_info_4x4"/>
         </receiver>
-        <receiver android:name=".receiver.MediaButtonIntentReceiver">
+        <receiver android:name=".receiver.MediaButtonIntentReceiver"
+            android:exported="false">
             <intent-filter android:priority="2147483647">
                 <action android:name="android.intent.action.MEDIA_BUTTON"/>
             </intent-filter>
         </receiver>
         <provider
             android:name=".provider.SearchSuggestionProvider"
-            android:authorities="org.moire.ultrasonic.provider.SearchSuggestionProvider"/>
+            android:authorities="org.moire.ultrasonic.provider.SearchSuggestionProvider"
+            android:exported="false" />
 
     </application>
 
diff --git a/ultrasonic/src/main/kotlin/org/moire/ultrasonic/playback/PlaybackService.kt b/ultrasonic/src/main/kotlin/org/moire/ultrasonic/playback/PlaybackService.kt
index f2b56c0a..5c675fbb 100644
--- a/ultrasonic/src/main/kotlin/org/moire/ultrasonic/playback/PlaybackService.kt
+++ b/ultrasonic/src/main/kotlin/org/moire/ultrasonic/playback/PlaybackService.kt
@@ -15,7 +15,6 @@
  */
 package org.moire.ultrasonic.playback
 
-import android.annotation.SuppressLint
 import android.app.PendingIntent
 import android.content.Intent
 import androidx.media3.common.AudioAttributes
@@ -135,11 +134,14 @@ class PlaybackService : MediaLibraryService(), KoinComponent {
             .build()
     }
 
-    @SuppressLint("UnspecifiedImmutableFlag")
     private fun getPendingIntentForContent(): PendingIntent {
         val intent = Intent(this, NavigationActivity::class.java)
             .addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP)
-        val flags = PendingIntent.FLAG_UPDATE_CURRENT
+        var flags = PendingIntent.FLAG_UPDATE_CURRENT
+        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.M) {
+            // needed starting Android 12 (S = 31)
+            flags = flags or PendingIntent.FLAG_IMMUTABLE
+        }
         intent.putExtra(Constants.INTENT_SHOW_PLAYER, true)
         return PendingIntent.getActivity(this, 0, intent, flags)
     }
diff --git a/ultrasonic/src/main/kotlin/org/moire/ultrasonic/provider/UltrasonicAppWidgetProvider.kt b/ultrasonic/src/main/kotlin/org/moire/ultrasonic/provider/UltrasonicAppWidgetProvider.kt
index 7a12fdfe..79a71759 100644
--- a/ultrasonic/src/main/kotlin/org/moire/ultrasonic/provider/UltrasonicAppWidgetProvider.kt
+++ b/ultrasonic/src/main/kotlin/org/moire/ultrasonic/provider/UltrasonicAppWidgetProvider.kt
@@ -7,7 +7,6 @@
 
 package org.moire.ultrasonic.provider
 
-import android.annotation.SuppressLint
 import android.app.PendingIntent
 import android.appwidget.AppWidgetManager
 import android.appwidget.AppWidgetProvider
@@ -164,7 +163,6 @@ open class UltrasonicAppWidgetProvider : AppWidgetProvider() {
         /**
          * Link up various button actions using [PendingIntent].
          */
-        @SuppressLint("UnspecifiedImmutableFlag")
         private fun linkButtons(context: Context, views: RemoteViews, playerActive: Boolean) {
             var intent = Intent(
                 context,
@@ -173,8 +171,13 @@ open class UltrasonicAppWidgetProvider : AppWidgetProvider() {
             if (playerActive) intent.putExtra(Constants.INTENT_SHOW_PLAYER, true)
             intent.action = "android.intent.action.MAIN"
             intent.addCategory("android.intent.category.LAUNCHER")
+            var flags = PendingIntent.FLAG_UPDATE_CURRENT
+            if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.M) {
+                // needed starting Android 12 (S = 31)
+                flags = flags or PendingIntent.FLAG_IMMUTABLE
+            }
             var pendingIntent =
-                PendingIntent.getActivity(context, 10, intent, PendingIntent.FLAG_UPDATE_CURRENT)
+                PendingIntent.getActivity(context, 10, intent, flags)
             views.setOnClickPendingIntent(R.id.appwidget_coverart, pendingIntent)
             views.setOnClickPendingIntent(R.id.appwidget_top, pendingIntent)
 
@@ -185,7 +188,12 @@ open class UltrasonicAppWidgetProvider : AppWidgetProvider() {
                 Intent.EXTRA_KEY_EVENT,
                 KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE)
             )
-            pendingIntent = PendingIntent.getBroadcast(context, 11, intent, 0)
+            flags = 0
+            if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.M) {
+                // needed starting Android 12 (S = 31)
+                flags = flags or PendingIntent.FLAG_IMMUTABLE
+            }
+            pendingIntent = PendingIntent.getBroadcast(context, 11, intent, flags)
             views.setOnClickPendingIntent(R.id.control_play, pendingIntent)
             intent = Intent(Constants.CMD_PROCESS_KEYCODE)
             intent.component = ComponentName(context, MediaButtonIntentReceiver::class.java)
@@ -193,7 +201,7 @@ open class UltrasonicAppWidgetProvider : AppWidgetProvider() {
                 Intent.EXTRA_KEY_EVENT,
                 KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_MEDIA_NEXT)
             )
-            pendingIntent = PendingIntent.getBroadcast(context, 12, intent, 0)
+            pendingIntent = PendingIntent.getBroadcast(context, 12, intent, flags)
             views.setOnClickPendingIntent(R.id.control_next, pendingIntent)
             intent = Intent(Constants.CMD_PROCESS_KEYCODE)
             intent.component = ComponentName(context, MediaButtonIntentReceiver::class.java)
@@ -201,7 +209,7 @@ open class UltrasonicAppWidgetProvider : AppWidgetProvider() {
                 Intent.EXTRA_KEY_EVENT,
                 KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_MEDIA_PREVIOUS)
             )
-            pendingIntent = PendingIntent.getBroadcast(context, 13, intent, 0)
+            pendingIntent = PendingIntent.getBroadcast(context, 13, intent, flags)
             views.setOnClickPendingIntent(R.id.control_previous, pendingIntent)
         }
     }
diff --git a/ultrasonic/src/main/kotlin/org/moire/ultrasonic/service/DownloadService.kt b/ultrasonic/src/main/kotlin/org/moire/ultrasonic/service/DownloadService.kt
index e9cc351d..5f3fcfe6 100644
--- a/ultrasonic/src/main/kotlin/org/moire/ultrasonic/service/DownloadService.kt
+++ b/ultrasonic/src/main/kotlin/org/moire/ultrasonic/service/DownloadService.kt
@@ -154,11 +154,14 @@ class DownloadService : Service() {
         return notificationBuilder.build()
     }
 
-    @SuppressLint("UnspecifiedImmutableFlag")
     private fun getPendingIntentForContent(): PendingIntent {
         val intent = Intent(this, NavigationActivity::class.java)
             .addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP)
-        val flags = PendingIntent.FLAG_UPDATE_CURRENT
+        var flags = PendingIntent.FLAG_UPDATE_CURRENT
+        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.M) {
+            // needed starting Android 12 (S = 31)
+            flags = flags or PendingIntent.FLAG_IMMUTABLE
+        }
         intent.putExtra(Constants.INTENT_SHOW_PLAYER, true)
         return PendingIntent.getActivity(this, 0, intent, flags)
     }