diff --git a/just_audio/example/lib/main.dart b/just_audio/example/lib/main.dart
index 85f7f6f..595da2f 100644
--- a/just_audio/example/lib/main.dart
+++ b/just_audio/example/lib/main.dart
@@ -284,7 +284,8 @@ class ControlButtons extends StatelessWidget {
               return IconButton(
                 icon: Icon(Icons.replay),
                 iconSize: 64.0,
-                onPressed: () => player.seek(Duration.zero, index: 0),
+                onPressed: () => player.seek(Duration.zero,
+                    index: player.effectiveIndices.first),
               );
             }
           },
diff --git a/just_audio/example/pubspec.lock b/just_audio/example/pubspec.lock
index e250a2a..4555a6b 100644
--- a/just_audio/example/pubspec.lock
+++ b/just_audio/example/pubspec.lock
@@ -7,7 +7,7 @@ packages:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.5.0-nullsafety.1"
+    version: "2.5.0-nullsafety.3"
   audio_session:
     dependency: "direct main"
     description:
@@ -21,35 +21,35 @@ packages:
       name: boolean_selector
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0-nullsafety.1"
+    version: "2.1.0-nullsafety.3"
   characters:
     dependency: transitive
     description:
       name: characters
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0-nullsafety.3"
+    version: "1.1.0-nullsafety.5"
   charcode:
     dependency: transitive
     description:
       name: charcode
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0-nullsafety.1"
+    version: "1.2.0-nullsafety.3"
   clock:
     dependency: transitive
     description:
       name: clock
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0-nullsafety.1"
+    version: "1.1.0-nullsafety.3"
   collection:
     dependency: transitive
     description:
       name: collection
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.15.0-nullsafety.3"
+    version: "1.15.0-nullsafety.5"
   convert:
     dependency: transitive
     description:
@@ -77,7 +77,7 @@ packages:
       name: fake_async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0-nullsafety.1"
+    version: "1.2.0-nullsafety.3"
   ffi:
     dependency: transitive
     description:
@@ -114,6 +114,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "0.16.1"
+  js:
+    dependency: transitive
+    description:
+      name: js
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.6.3-nullsafety.3"
   just_audio:
     dependency: "direct main"
     description:
@@ -141,21 +148,21 @@ packages:
       name: matcher
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.10-nullsafety.1"
+    version: "0.12.10-nullsafety.3"
   meta:
     dependency: transitive
     description:
       name: meta
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.0-nullsafety.3"
+    version: "1.3.0-nullsafety.6"
   path:
     dependency: transitive
     description:
       name: path
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.8.0-nullsafety.1"
+    version: "1.8.0-nullsafety.3"
   path_provider:
     dependency: transitive
     description:
@@ -230,49 +237,49 @@ packages:
       name: source_span
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.8.0-nullsafety.2"
+    version: "1.8.0-nullsafety.4"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.10.0-nullsafety.1"
+    version: "1.10.0-nullsafety.6"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0-nullsafety.1"
+    version: "2.1.0-nullsafety.3"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0-nullsafety.1"
+    version: "1.1.0-nullsafety.3"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0-nullsafety.1"
+    version: "1.2.0-nullsafety.3"
   test_api:
     dependency: transitive
     description:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.19-nullsafety.2"
+    version: "0.2.19-nullsafety.6"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.0-nullsafety.3"
+    version: "1.3.0-nullsafety.5"
   uuid:
     dependency: transitive
     description:
@@ -286,7 +293,7 @@ packages:
       name: vector_math
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0-nullsafety.3"
+    version: "2.1.0-nullsafety.5"
   win32:
     dependency: transitive
     description:
@@ -302,5 +309,5 @@ packages:
     source: hosted
     version: "0.1.2"
 sdks:
-  dart: ">=2.10.0-110 <2.11.0"
+  dart: ">=2.12.0-0.0 <3.0.0"
   flutter: ">=1.12.13+hotfix.5 <2.0.0"
diff --git a/just_audio/lib/just_audio.dart b/just_audio/lib/just_audio.dart
index 639a866..262967d 100644
--- a/just_audio/lib/just_audio.dart
+++ b/just_audio/lib/just_audio.dart
@@ -105,7 +105,6 @@ class AudioPlayer {
         .map((event) => event.currentIndex)
         .distinct()
         .handleError((err, stack) {/* noop */}));
-    currentIndexStream.listen((index) => print('### index: $index'));
     _androidAudioSessionIdSubject.addStream(playbackEventStream
         .map((event) => event.androidAudioSessionId)
         .distinct()
@@ -154,8 +153,6 @@ class AudioPlayer {
           currentIndex: message.currentIndex,
           androidAudioSessionId: message.androidAudioSessionId,
         );
-        print(
-            "### received event with currentIndex: ${playbackEvent.currentIndex}");
         _durationFuture = Future.value(playbackEvent.duration);
         if (playbackEvent.duration != _playbackEvent.duration) {
           _durationSubject.add(playbackEvent.duration);
@@ -308,69 +305,48 @@ class AudioPlayer {
   Stream<SequenceState> get sequenceStateStream => _sequenceStateSubject.stream;
 
   /// Whether there is another item after the current index.
-  bool get hasNext => _nextIndex != null;
+  bool get hasNext => nextIndex != null;
 
   /// Whether there is another item before the current index.
-  bool get hasPrevious => _previousIndex != null;
+  bool get hasPrevious => previousIndex != null;
 
-  int get _nextIndex => _getRelativeIndex(1);
-  int get _previousIndex => _getRelativeIndex(-1);
+  /// Returns [shuffleIndices] if [shuffleModeEnabled] is `true`, otherwise
+  /// returns the unshuffled indices.
+  List<int> get effectiveIndices {
+    if (shuffleIndices == null || sequence == null) return null;
+    return shuffleModeEnabled
+        ? shuffleIndices
+        : List.generate(sequence.length, (i) => i);
+  }
+
+  List<int> get _effectiveIndicesInv {
+    if (shuffleIndices == null || sequence == null) return null;
+    return shuffleModeEnabled
+        ? _shuffleIndicesInv
+        : List.generate(sequence.length, (i) => i);
+  }
+
+  int get nextIndex => _getRelativeIndex(1);
+  int get previousIndex => _getRelativeIndex(-1);
 
   int _getRelativeIndex(int offset) {
-    print('### _getRelativeIndex');
-    print('audioSource = $_audioSource');
-    print('currentIndex = $currentIndex');
-    print('shuffleModeEnabled = $shuffleModeEnabled');
     if (_audioSource == null ||
         currentIndex == null ||
         shuffleModeEnabled == null) return null;
     if (loopMode == LoopMode.one) return currentIndex;
-    int result;
-    print('shuffleModeEnabled: $shuffleModeEnabled');
-    if (shuffleModeEnabled) {
-      print('shuffleIndices: $shuffleIndices');
-      print('shuffleIndicesInv: $_shuffleIndicesInv');
-      if (shuffleIndices == null) return null;
-      final shufflePos = _shuffleIndicesInv[currentIndex];
-      var newShufflePos = shufflePos + offset;
-      print(
-          'newshufflePos($newShufflePos) >= shuffleIndices.length(${shuffleIndices.length})');
-      if (newShufflePos >= shuffleIndices.length) {
-        if (loopMode == LoopMode.all) {
-          newShufflePos = 0;
-        } else {
-          return null;
-        }
-      }
-      if (newShufflePos < 0) {
-        if (loopMode == LoopMode.all) {
-          newShufflePos = shuffleIndices.length - 1;
-        } else {
-          return null;
-        }
-      }
-      result = shuffleIndices[newShufflePos];
-    } else {
-      print("sequence: $sequence");
-      if (sequence == null) return null;
-      result = currentIndex + offset;
-      print("result($result >= sequence.length(${sequence.length}))");
-      if (result >= sequence.length) {
-        if (loopMode == LoopMode.all) {
-          result = 0;
-        } else {
-          return null;
-        }
-      }
-      if (result < 0) {
-        if (loopMode == LoopMode.all) {
-          result = sequence.length - 1;
-        } else {
-          return null;
-        }
+    final effectiveIndices = this.effectiveIndices;
+    if (effectiveIndices == null) return null;
+    final effectiveIndicesInv = _effectiveIndicesInv;
+    final invPos = effectiveIndicesInv[currentIndex];
+    var newInvPos = invPos + offset;
+    if (newInvPos >= effectiveIndices.length || newInvPos < 0) {
+      if (loopMode == LoopMode.all) {
+        newInvPos %= effectiveIndices.length;
+      } else {
+        return null;
       }
     }
-    print("returning $result");
+    final result = effectiveIndices[newInvPos];
     return result;
   }
 
@@ -535,7 +511,6 @@ class AudioPlayer {
     if (_disposed) return null;
     try {
       _audioSource = source;
-      print("### set _audioSource = $_audioSource");
       _broadcastSequence();
       final duration = await _load(source,
           initialPosition: initialPosition, initialIndex: initialIndex);
@@ -550,18 +525,12 @@ class AudioPlayer {
   }
 
   void _broadcastSequence() {
-    print("### _broadcastSequence");
     _sequenceSubject.add(_audioSource?.sequence);
-
-    print('sequence: ${_audioSource?.sequence?.length}');
-
     _updateShuffleIndices();
   }
 
   _updateShuffleIndices() {
     _shuffleIndicesSubject.add(_audioSource?.shuffleIndices);
-    print('shuffle indices: ${_audioSource?.shuffleIndices?.length}');
-    print('shuffleIndices: ${shuffleIndices?.length}');
     final shuffleIndicesLength = shuffleIndices?.length ?? 0;
     if (_shuffleIndicesInv.length > shuffleIndicesLength) {
       _shuffleIndicesInv.removeRange(
@@ -573,7 +542,6 @@ class AudioPlayer {
     for (var i = 0; i < shuffleIndicesLength; i++) {
       _shuffleIndicesInv[shuffleIndices[i]] = i;
     }
-    print('shuffleIndicesInv: ${_shuffleIndicesInv?.length}');
   }
 
   _registerAudioSource(AudioSource source) {
@@ -582,7 +550,6 @@ class AudioPlayer {
 
   Future<Duration> _load(AudioSource source,
       {Duration initialPosition, int initialIndex}) async {
-    print("### _load with initialIndex=$initialIndex");
     try {
       if (!kIsWeb && source._requiresHeaders) {
         if (_proxy == null) {
@@ -732,13 +699,10 @@ class AudioPlayer {
 
   /// Recursively shuffles the children of the currently loaded [AudioSource].
   Future<void> shuffle() async {
-    print(
-        "shuffle. _disposed: $_disposed, currentIndex: $currentIndex, _audioSource: $_audioSource");
     if (_disposed) return;
     if (_audioSource == null) return;
     _audioSource._shuffle(initialIndex: currentIndex);
     _updateShuffleIndices();
-    print("Shuffle: $shuffleIndices");
     await (await _platform).setShuffleOrder(
         SetShuffleOrderRequest(audioSourceMessage: _audioSource._toMessage()));
   }
@@ -776,19 +740,17 @@ class AudioPlayer {
     }
   }
 
-  /// Seek to the next item.
+  /// Seek to the next item, or does nothing if there is no next item.
   Future<void> seekToNext() async {
-    if (_disposed) return;
     if (hasNext) {
-      await seek(Duration.zero, index: _nextIndex);
+      await seek(Duration.zero, index: nextIndex);
     }
   }
 
-  /// Seek to the previous item.
+  /// Seek to the previous item, or does nothing if there is no previous item.
   Future<void> seekToPrevious() async {
-    if (_disposed) return;
     if (hasPrevious) {
-      await seek(Duration.zero, index: _previousIndex);
+      await seek(Duration.zero, index: previousIndex);
     }
   }
 
@@ -817,7 +779,6 @@ class AudioPlayer {
       await (await _platform).dispose(DisposeRequest());
     }
     _audioSource = null;
-    print("### set _audioSource = $_audioSource (dispose)");
     _audioSources.values.forEach((s) => s._dispose());
     _audioSources.clear();
     _proxy?.stop();
@@ -1445,8 +1406,6 @@ class ConcatenatingAudioSource extends AudioSource {
       child._shuffle(initialIndex: childInitialIndex);
       si += childLength;
     }
-    print(
-        "cat _shuffle (initialIndex=$initialIndex, localInitialIndex=$localInitialIndex)");
     _shuffleOrder.shuffle(initialIndex: localInitialIndex);
   }
 
@@ -1603,11 +1562,8 @@ class ConcatenatingAudioSource extends AudioSource {
     }
     final indices = <int>[];
     for (var index in _shuffleOrder.indices) {
-      final childIndices = childIndicesList[index];
-      //print("child indices: $childIndices");
-      indices.addAll(childIndices);
+      indices.addAll(childIndicesList[index]);
     }
-    print("### returning: $indices");
     return indices;
   }
 
@@ -1728,11 +1684,8 @@ class DefaultShuffleOrder extends ShuffleOrder {
   @override
   void shuffle({int initialIndex}) {
     assert(initialIndex == null || indices.contains(initialIndex));
-    print(
-        "### order shuffle, initialIndex: $initialIndex (existing: $indices)");
     if (indices.length <= 1) return;
     indices.shuffle(_random);
-    print("now $indices");
     if (initialIndex == null) return;
 
     final initialPos = 0;
@@ -1741,7 +1694,6 @@ class DefaultShuffleOrder extends ShuffleOrder {
     final swapIndex = indices[initialPos];
     indices[initialPos] = initialIndex;
     indices[swapPos] = swapIndex;
-    print("final $indices");
   }
 
   @override
diff --git a/just_audio/pubspec.lock b/just_audio/pubspec.lock
index ac41e92..df82919 100644
--- a/just_audio/pubspec.lock
+++ b/just_audio/pubspec.lock
@@ -28,7 +28,7 @@ packages:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.5.0-nullsafety.1"
+    version: "2.5.0-nullsafety.3"
   audio_session:
     dependency: "direct main"
     description:
@@ -42,7 +42,7 @@ packages:
       name: boolean_selector
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0-nullsafety.1"
+    version: "2.1.0-nullsafety.3"
   build:
     dependency: transitive
     description:
@@ -70,14 +70,14 @@ packages:
       name: characters
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0-nullsafety.3"
+    version: "1.1.0-nullsafety.5"
   charcode:
     dependency: transitive
     description:
       name: charcode
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0-nullsafety.1"
+    version: "1.2.0-nullsafety.3"
   cli_util:
     dependency: transitive
     description:
@@ -91,7 +91,7 @@ packages:
       name: clock
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0-nullsafety.1"
+    version: "1.1.0-nullsafety.3"
   code_builder:
     dependency: transitive
     description:
@@ -105,7 +105,7 @@ packages:
       name: collection
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.15.0-nullsafety.3"
+    version: "1.15.0-nullsafety.5"
   convert:
     dependency: transitive
     description:
@@ -133,7 +133,7 @@ packages:
       name: fake_async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0-nullsafety.1"
+    version: "1.2.0-nullsafety.3"
   ffi:
     dependency: transitive
     description:
@@ -190,7 +190,7 @@ packages:
       name: js
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.6.2"
+    version: "0.6.3-nullsafety.3"
   just_audio_platform_interface:
     dependency: "direct main"
     description:
@@ -218,14 +218,14 @@ packages:
       name: matcher
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.10-nullsafety.1"
+    version: "0.12.10-nullsafety.3"
   meta:
     dependency: transitive
     description:
       name: meta
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.0-nullsafety.3"
+    version: "1.3.0-nullsafety.6"
   mockito:
     dependency: "direct dev"
     description:
@@ -260,7 +260,7 @@ packages:
       name: path
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.8.0-nullsafety.1"
+    version: "1.8.0-nullsafety.3"
   path_provider:
     dependency: "direct main"
     description:
@@ -363,49 +363,49 @@ packages:
       name: source_span
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.8.0-nullsafety.2"
+    version: "1.8.0-nullsafety.4"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.10.0-nullsafety.1"
+    version: "1.10.0-nullsafety.6"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0-nullsafety.1"
+    version: "2.1.0-nullsafety.3"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0-nullsafety.1"
+    version: "1.1.0-nullsafety.3"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0-nullsafety.1"
+    version: "1.2.0-nullsafety.3"
   test_api:
     dependency: transitive
     description:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.19-nullsafety.2"
+    version: "0.2.19-nullsafety.6"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.0-nullsafety.3"
+    version: "1.3.0-nullsafety.5"
   uuid:
     dependency: "direct main"
     description:
@@ -419,7 +419,7 @@ packages:
       name: vector_math
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0-nullsafety.3"
+    version: "2.1.0-nullsafety.5"
   watcher:
     dependency: transitive
     description:
@@ -449,5 +449,5 @@ packages:
     source: hosted
     version: "2.2.1"
 sdks:
-  dart: ">=2.10.0 <2.11.0"
+  dart: ">=2.12.0-0.0 <3.0.0"
   flutter: ">=1.12.13+hotfix.5 <2.0.0"