diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9738980..64a7698 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -29,4 +29,10 @@
 * Add ability to listen to neighbour locations
 
 ## 0.4.0
-* Add ability to listen (and stop listening) to significant location updates
\ No newline at end of file
+* Add ability to listen (and stop listening) to significant location updates
+
+## 0.4.1
+* null safety
+* Add result calls to iOS platform code (#36) - Thanks @geisterfurz007
+* Added documentation regarding geofence constraints (#34) - Thanks @rodrigonso
+* Add comment indicating unit of measure for radius (#33) - Thanks @turing-tech
diff --git a/example/lib/main.dart b/example/lib/main.dart
index 83c6c45..7889ed6 100644
--- a/example/lib/main.dart
+++ b/example/lib/main.dart
@@ -29,8 +29,8 @@ class _MyAppState extends State<MyApp> {
         new AndroidInitializationSettings('app_icon');
     var initializationSettingsIOS =
         IOSInitializationSettings(onDidReceiveLocalNotification: null);
-    var initializationSettings = InitializationSettings(android:
-        initializationSettingsAndroid, iOS: initializationSettingsIOS);
+    var initializationSettings = InitializationSettings(
+        android: initializationSettingsAndroid, iOS: initializationSettingsIOS);
     flutterLocalNotificationsPlugin.initialize(initializationSettings,
         onSelectNotification: null);
   }
@@ -149,8 +149,9 @@ class _MyAppState extends State<MyApp> {
           priority: Priority.high,
           ticker: 'ticker');
       var iOSPlatformChannelSpecifics = IOSNotificationDetails();
-      var platformChannelSpecifics = NotificationDetails(android:
-          androidPlatformChannelSpecifics, iOS: iOSPlatformChannelSpecifics);
+      var platformChannelSpecifics = NotificationDetails(
+          android: androidPlatformChannelSpecifics,
+          iOS: iOSPlatformChannelSpecifics);
       await flutterLocalNotificationsPlugin.show(
           rng.nextInt(100000), title, subtitle, platformChannelSpecifics,
           payload: 'item x');
diff --git a/example/pubspec.lock b/example/pubspec.lock
index 5364419..f1a3f8a 100644
--- a/example/pubspec.lock
+++ b/example/pubspec.lock
@@ -68,7 +68,7 @@ packages:
       path: ".."
       relative: true
     source: path
-    version: "0.4.0"
+    version: "0.4.1"
   flutter_local_notifications:
     dependency: "direct main"
     description:
@@ -193,4 +193,4 @@ packages:
     version: "2.1.0"
 sdks:
   dart: ">=2.12.0-0.0 <3.0.0"
-  flutter: ">=1.12.13+hotfix.5"
+  flutter: ">=1.22.0"
diff --git a/lib/Geolocation.dart b/lib/Geolocation.dart
index a958d50..2a9b365 100644
--- a/lib/Geolocation.dart
+++ b/lib/Geolocation.dart
@@ -4,7 +4,11 @@ class Geolocation {
   final double radius; // in meters
   final String id;
 
-  const Geolocation({required this.latitude, required this.longitude, required this.radius, required this.id});
+  const Geolocation(
+      {required this.latitude,
+      required this.longitude,
+      required this.radius,
+      required this.id});
 }
 
 enum GeolocationEvent { entry, exit }
diff --git a/lib/geofence.dart b/lib/geofence.dart
index 5d02dcd..243101c 100644
--- a/lib/geofence.dart
+++ b/lib/geofence.dart
@@ -17,8 +17,8 @@ class Coordinate {
 class Geofence {
   static const MethodChannel _channel = const MethodChannel('geofence');
 
-  static GeofenceCallback _entryCallback = (location){};
-  static GeofenceCallback _exitCallback = (location){};
+  static GeofenceCallback _entryCallback = (location) {};
+  static GeofenceCallback _exitCallback = (location) {};
 
   //ignore: close_sinks
   static StreamController<Coordinate> _userLocationUpdated =
@@ -86,7 +86,7 @@ class Geofence {
             longitude: call.arguments["longitude"] as double,
             radius: call.arguments["radius"] as double,
             id: call.arguments["id"] as String);
-         _entryCallback(location);
+        _entryCallback(location);
       } else if (call.method == "exit") {
         Geolocation location = Geolocation(
             latitude: call.arguments["latitude"] as double,
diff --git a/pubspec.lock b/pubspec.lock
index 52ed0ad..178922e 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -144,4 +144,4 @@ packages:
     version: "2.1.0"
 sdks:
   dart: ">=2.12.0-0.0 <3.0.0"
-  flutter: ">=1.12.0"
+  flutter: ">=1.22.0"
diff --git a/pubspec.yaml b/pubspec.yaml
index 1a06dbf..a04fa60 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,11 +1,11 @@
 name: flutter_geofence
 description: Plugin to interact with geofences, and get the user's current/latest location.
-version: 0.4.0
+version: 0.4.1
 homepage: https://github.com/DwayneCoussement/geofence
 
 environment:
-  sdk: ">=2.12.0-0 <3.0.0"
-  flutter: ">=1.12.0 <2.0.0"
+  sdk: ">=2.12.0 <3.0.0"
+  flutter: ">=1.22.0"
 
 dependencies:
   flutter: