diff --git a/CHANGELOG.md b/CHANGELOG.md
index 60400e0..24564ed 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@
   available.
 * Remove `StreamChannelTransformer.typed`. Use `.cast` on the transformed
   channel instead.
+* Change `Future<dynamic>` returns to `Future<void>`.
 
 ## 1.7.0
 
diff --git a/lib/src/close_guarantee_channel.dart b/lib/src/close_guarantee_channel.dart
index c534a91..33296da 100644
--- a/lib/src/close_guarantee_channel.dart
+++ b/lib/src/close_guarantee_channel.dart
@@ -77,7 +77,7 @@
   _CloseGuaranteeSink(StreamSink<T> inner, this._channel) : super(inner);
 
   @override
-  Future close() {
+  Future<void> close() {
     var done = super.close();
     _channel._disconnected = true;
     if (_channel._subscription != null) {
diff --git a/lib/src/disconnector.dart b/lib/src/disconnector.dart
index 83defb8..69fbab7 100644
--- a/lib/src/disconnector.dart
+++ b/lib/src/disconnector.dart
@@ -33,7 +33,7 @@
   /// Returns a future that completes when all inner sinks' [StreamSink.close]
   /// futures have completed. Note that a [StreamController]'s sink won't close
   /// until the corresponding stream has a listener.
-  Future disconnect() => _disconnectMemo.runOnce(() {
+  Future<void> disconnect() => _disconnectMemo.runOnce(() {
         var futures = _sinks.map((sink) => sink._disconnect()).toList();
         _sinks.clear();
         return Future.wait(futures, eagerError: true);
@@ -64,7 +64,7 @@
   final StreamSink<T> _inner;
 
   @override
-  Future get done => _inner.done;
+  Future<void> get done => _inner.done;
 
   /// Whether [Disconnector.disconnect] has been called.
   var _isDisconnected = false;
@@ -108,7 +108,7 @@
   }
 
   @override
-  Future addStream(Stream<T> stream) {
+  Future<void> addStream(Stream<T> stream) {
     if (_closed) throw StateError("Cannot add stream after closing.");
     if (_inAddStream) {
       throw StateError("Cannot add stream while adding stream.");
@@ -125,7 +125,7 @@
   }
 
   @override
-  Future close() {
+  Future<void> close() {
     if (_inAddStream) {
       throw StateError("Cannot close sink while adding stream.");
     }
@@ -138,7 +138,7 @@
   ///
   /// This closes the underlying sink and stops forwarding events. It returns
   /// the [StreamSink.close] future for the underlying sink.
-  Future _disconnect() {
+  Future<void> _disconnect() {
     _isDisconnected = true;
     var future = _inner.close();
 
diff --git a/lib/src/guarantee_channel.dart b/lib/src/guarantee_channel.dart
index ce7f707..d8add39 100644
--- a/lib/src/guarantee_channel.dart
+++ b/lib/src/guarantee_channel.dart
@@ -81,7 +81,7 @@
   final GuaranteeChannel<T> _channel;
 
   @override
-  Future get done => _doneCompleter.future;
+  Future<void> get done => _doneCompleter.future;
   final _doneCompleter = Completer();
 
   /// Whether connection is disconnected.
@@ -157,7 +157,7 @@
   }
 
   @override
-  Future addStream(Stream<T> stream) {
+  Future<void> addStream(Stream<T> stream) {
     if (_closed) throw StateError("Cannot add stream after closing.");
     if (_inAddStream) {
       throw StateError("Cannot add stream while adding stream.");
@@ -174,7 +174,7 @@
   }
 
   @override
-  Future close() {
+  Future<void> close() {
     if (_inAddStream) {
       throw StateError("Cannot close sink while adding stream.");
     }
diff --git a/test/disconnector_test.dart b/test/disconnector_test.dart
index aefad28..0992b36 100644
--- a/test/disconnector_test.dart
+++ b/test/disconnector_test.dart
@@ -145,7 +145,7 @@
   _CloseCompleterSink(StreamSink inner) : super(inner);
 
   @override
-  Future close() {
+  Future<void> close() {
     super.close();
     return completer.future;
   }