diff --git a/packages/flutterfire_authenticator/lib/src/authenticator.dart b/packages/flutterfire_authenticator/lib/src/authenticator.dart
index 5a963ed..112d565 100644
--- a/packages/flutterfire_authenticator/lib/src/authenticator.dart
+++ b/packages/flutterfire_authenticator/lib/src/authenticator.dart
@@ -29,6 +29,9 @@ class Authenticator {
   /// 現在サインイン中のユーザー。サインインしていない場合はnullを返す。
   User? get user => _auth.currentUser;
 
+  /// Listens for changes to the currently signed-in user.
+  late final Stream<User?> userChanges = _auth.userChanges();
+
   /// 現ユーザーのJWT(JSON Web Token)を非同期で取得する。
   /// 未サインイン時など、現ユーザーが存在しない場合はnullを返す。
   Future<String?>? get fetchJwt => _auth.currentUser?.getIdToken();
diff --git a/packages/flutterfire_authenticator/test/authenticator_test.dart b/packages/flutterfire_authenticator/test/authenticator_test.dart
index 4cbdb8a..54783fb 100644
--- a/packages/flutterfire_authenticator/test/authenticator_test.dart
+++ b/packages/flutterfire_authenticator/test/authenticator_test.dart
@@ -14,6 +14,7 @@ void main() {
 class MockAuth extends Fake implements FirebaseAuth {}
 
 // TODO(riscait): add more tests
+// https://github.com/altive/flutterfire_adapter/issues/20
 // related links:
 // https://github.com/firebase/flutterfire/blob/master/packages/firebase_auth/firebase_auth/test/firebase_auth_test.dart
 // setupFirebaseAuthMocks