diff --git a/lib/global.dart b/lib/global.dart
index 0f8081a..061ae99 100644
--- a/lib/global.dart
+++ b/lib/global.dart
@@ -120,9 +120,9 @@ class VikunjaGlobalState extends State<VikunjaGlobal> {
         });
         return;
       }
-      loadedCurrentUser = User(int.tryParse(currentUser), "", "", "");
+      loadedCurrentUser = User(int.tryParse(currentUser), "", "");
     } catch (otherExceptions) {
-      loadedCurrentUser = User(int.tryParse(currentUser), "", "", "");
+      loadedCurrentUser = User(int.tryParse(currentUser), "", "");
     }
     setState(() {
       _client = client;
diff --git a/lib/models/list.dart b/lib/models/list.dart
index cf9a5ad..4578c4d 100644
--- a/lib/models/list.dart
+++ b/lib/models/list.dart
@@ -23,8 +23,8 @@ class TaskList {
         owner = User.fromJson(json['owner']),
         description = json['description'],
         title = json['title'],
-        updated = DateTime.fromMillisecondsSinceEpoch(json['updated']),
-        created = DateTime.fromMillisecondsSinceEpoch(json['created']),
+        updated = DateTime.parse(json['updated']),
+        created = DateTime.parse(json['created']),
         tasks = (json['tasks'] == null ? [] : json['tasks'] as List<dynamic>)
             ?.map((taskJson) => Task.fromJson(taskJson))
             ?.toList();
@@ -35,8 +35,8 @@ class TaskList {
       "title": this.title,
       "description": this.description,
       "owner": this.owner?.toJSON(),
-      "created": this.created?.millisecondsSinceEpoch,
-      "updated": this.updated?.millisecondsSinceEpoch,
+      "created": this.created?.toIso8601String(),
+      "updated": this.updated?.toIso8601String(),
     };
   }
 }
diff --git a/lib/models/namespace.dart b/lib/models/namespace.dart
index 700d2d7..f271914 100644
--- a/lib/models/namespace.dart
+++ b/lib/models/namespace.dart
@@ -19,13 +19,13 @@ class Namespace {
       : name = json['name'],
         description = json['description'],
         id = json['id'],
-        created = DateTime.fromMillisecondsSinceEpoch(json['created']),
-        updated = DateTime.fromMillisecondsSinceEpoch(json['updated']),
+        created = DateTime.parse(json['created']),
+        updated = DateTime.parse(json['updated']),
         owner = User.fromJson(json['owner']);
 
   toJSON() => {
-        "created": created?.millisecondsSinceEpoch,
-        "updated": updated?.millisecondsSinceEpoch,
+        "created": created?.toIso8601String(),
+        "updated": updated?.toIso8601String(),
         "name": name,
         "owner": owner?.toJSON(),
         "description": description
diff --git a/lib/models/task.dart b/lib/models/task.dart
index 897f63e..0a83f7a 100644
--- a/lib/models/task.dart
+++ b/lib/models/task.dart
@@ -22,12 +22,12 @@ class Task {
 
   Task.fromJson(Map<String, dynamic> json)
       : id = json['id'],
-        updated = DateTime.fromMillisecondsSinceEpoch(json['updated']),
-        created = DateTime.fromMillisecondsSinceEpoch(json['created']),
+        updated = DateTime.parse(json['updated']),
+        created = DateTime.parse(json['created']),
         reminders = (json['reminderDates'] as List<dynamic>)
-            ?.map((milli) => DateTime.fromMillisecondsSinceEpoch(milli))
+            ?.map((r) => DateTime.parse(r))
             ?.toList(),
-        due = DateTime.fromMillisecondsSinceEpoch(json['dueDate']),
+        due = DateTime.parse(json['dueDate']),
         description = json['description'],
         text = json['text'],
         done = json['done'],
@@ -35,11 +35,11 @@ class Task {
 
   toJSON() => {
         'id': id,
-        'updated': updated?.millisecondsSinceEpoch,
-        'created': created?.millisecondsSinceEpoch,
+        'updated': updated?.toIso8601String(),
+        'created': created?.toIso8601String(),
         'reminderDates':
-            reminders?.map((date) => date.millisecondsSinceEpoch)?.toList(),
-        'dueDate': due?.millisecondsSinceEpoch,
+            reminders?.map((date) => date.toIso8601String())?.toList(),
+        'dueDate': due?.toIso8601String(),
         'description': description,
         'text': text,
         'done': done ?? false,
diff --git a/lib/models/user.dart b/lib/models/user.dart
index 17f7639..08b0280 100644
--- a/lib/models/user.dart
+++ b/lib/models/user.dart
@@ -1,18 +1,20 @@
+import 'package:flutter/cupertino.dart';
+import 'package:vikunja_app/global.dart';
+
 class User {
   final int id;
-  final String email, username, avatarHash;
+  final String email, username;
 
-  User(this.id, this.email, this.username, this.avatarHash);
+  User(this.id, this.email, this.username);
   User.fromJson(Map<String, dynamic> json)
       : id = json['id'],
         email = json.containsKey('email') ? json['email'] : '',
-        username = json['username'],
-        avatarHash = json['avatarUrl'];
+        username = json['username'];
 
   toJSON() => {"id": this.id, "email": this.email, "username": this.username};
 
-  String avatarUrl() {
-    return "https://secure.gravatar.com/avatar/" + this.avatarHash;
+  String avatarUrl(BuildContext context) {
+    return VikunjaGlobal.of(context).client.base + "/" + this.username + "/avatar";
   }
 }
 
diff --git a/lib/pages/home.dart b/lib/pages/home.dart
index e37c07e..089cf07 100644
--- a/lib/pages/home.dart
+++ b/lib/pages/home.dart
@@ -101,7 +101,7 @@ class HomePageState extends State<HomePage> with AfterLayoutMixin<HomePage> {
           currentAccountPicture: currentUser == null
               ? null
               : CircleAvatar(
-                  backgroundImage: NetworkImage(currentUser.avatarUrl()),
+                  backgroundImage: NetworkImage(currentUser.avatarUrl(context)),
                 ),
           decoration: BoxDecoration(
             image: DecorationImage(
diff --git a/lib/service/mocked_services.dart b/lib/service/mocked_services.dart
index 98913e1..35d5fbb 100644
--- a/lib/service/mocked_services.dart
+++ b/lib/service/mocked_services.dart
@@ -7,7 +7,7 @@ import 'package:vikunja_app/models/user.dart';
 import 'package:vikunja_app/service/services.dart';
 
 // Data for mocked services
-var _users = {1: User(1, 'test@testuser.org', 'test1', '')};
+var _users = {1: User(1, 'test@testuser.org', 'test1')};
 
 var _namespaces = {
   1: Namespace(