diff --git a/src/DotTiled.Tests/Assert/AssertData.cs b/src/DotTiled.Tests/Assert/AssertData.cs
index 3207a20..d840ae0 100644
--- a/src/DotTiled.Tests/Assert/AssertData.cs
+++ b/src/DotTiled.Tests/Assert/AssertData.cs
@@ -2,7 +2,7 @@ namespace DotTiled.Tests;
 
 public static partial class DotTiledAssert
 {
-  internal static void AssertData(Data? expected, Data? actual)
+  internal static void AssertData(Data expected, Data actual)
   {
     if (expected is null)
     {
diff --git a/src/DotTiled.Tests/Assert/AssertImage.cs b/src/DotTiled.Tests/Assert/AssertImage.cs
index a674faa..6bb5f4e 100644
--- a/src/DotTiled.Tests/Assert/AssertImage.cs
+++ b/src/DotTiled.Tests/Assert/AssertImage.cs
@@ -2,7 +2,7 @@ namespace DotTiled.Tests;
 
 public static partial class DotTiledAssert
 {
-  internal static void AssertImage(Image? expected, Image? actual)
+  internal static void AssertImage(Image expected, Image actual)
   {
     if (expected is null)
     {
diff --git a/src/DotTiled.Tests/Assert/AssertLayer.cs b/src/DotTiled.Tests/Assert/AssertLayer.cs
index 5432d62..7dc8011 100644
--- a/src/DotTiled.Tests/Assert/AssertLayer.cs
+++ b/src/DotTiled.Tests/Assert/AssertLayer.cs
@@ -2,7 +2,7 @@ namespace DotTiled.Tests;
 
 public static partial class DotTiledAssert
 {
-  internal static void AssertLayer(BaseLayer? expected, BaseLayer? actual)
+  internal static void AssertLayer(BaseLayer expected, BaseLayer actual)
   {
     if (expected is null)
     {
diff --git a/src/DotTiled.Tests/Assert/AssertProperties.cs b/src/DotTiled.Tests/Assert/AssertProperties.cs
index 843d8d0..9454486 100644
--- a/src/DotTiled.Tests/Assert/AssertProperties.cs
+++ b/src/DotTiled.Tests/Assert/AssertProperties.cs
@@ -2,7 +2,7 @@ namespace DotTiled.Tests;
 
 public static partial class DotTiledAssert
 {
-  internal static void AssertProperties(IList<IProperty>? expected, IList<IProperty>? actual)
+  internal static void AssertProperties(IList<IProperty> expected, IList<IProperty> actual)
   {
     if (expected is null)
     {
diff --git a/src/DotTiled.Tests/Assert/AssertTileset.cs b/src/DotTiled.Tests/Assert/AssertTileset.cs
index 0c10279..607b542 100644
--- a/src/DotTiled.Tests/Assert/AssertTileset.cs
+++ b/src/DotTiled.Tests/Assert/AssertTileset.cs
@@ -43,7 +43,7 @@ public static partial class DotTiledAssert
     AssertEqual(expected.Y, actual.Y, nameof(TileOffset.Y));
   }
 
-  private static void AssertGrid(Grid? expected, Grid? actual)
+  private static void AssertGrid(Grid expected, Grid actual)
   {
     if (expected is null)
     {
@@ -86,7 +86,7 @@ public static partial class DotTiledAssert
     AssertEqual(expected.WangID, actual.WangID, nameof(WangTile.WangID));
   }
 
-  private static void AssertTransformations(Transformations? expected, Transformations? actual)
+  private static void AssertTransformations(Transformations expected, Transformations actual)
   {
     if (expected is null)
     {
diff --git a/src/DotTiled.Tests/Serialization/MapReaderTests.cs b/src/DotTiled.Tests/Serialization/MapReaderTests.cs
index 0f365ab..885f57e 100644
--- a/src/DotTiled.Tests/Serialization/MapReaderTests.cs
+++ b/src/DotTiled.Tests/Serialization/MapReaderTests.cs
@@ -5,7 +5,7 @@ namespace DotTiled.Tests;
 public partial class MapReaderTests
 {
   public static IEnumerable<object[]> Maps => TestData.MapTests;
-  [Theory(Skip = "Skipped for now")]
+  [Theory]
   [MemberData(nameof(Maps))]
   public void MapReaderReadMap_ValidFilesExternalTilesetsAndTemplates_ReturnsMapThatEqualsExpected(
     string testDataFile,
diff --git a/src/DotTiled/Serialization/Tmj/ExtensionsJsonElement.cs b/src/DotTiled/Serialization/Tmj/ExtensionsJsonElement.cs
index 0e76d84..23951de 100644
--- a/src/DotTiled/Serialization/Tmj/ExtensionsJsonElement.cs
+++ b/src/DotTiled/Serialization/Tmj/ExtensionsJsonElement.cs
@@ -15,13 +15,13 @@ internal static class ExtensionsJsonElement
     return property.GetValueAs<T>();
   }
 
-  internal static T GetOptionalProperty<T>(this JsonElement element, string propertyName, T defaultValue)
+  internal static Optional<T> GetOptionalProperty<T>(this JsonElement element, string propertyName)
   {
     if (!element.TryGetProperty(propertyName, out var property))
-      return defaultValue;
+      return Optional<T>.Empty;
 
     if (property.ValueKind == JsonValueKind.Null)
-      return defaultValue;
+      return Optional<T>.Empty;
 
     return property.GetValueAs<T>();
   }
@@ -64,18 +64,18 @@ internal static class ExtensionsJsonElement
     return parser(property.GetString()!);
   }
 
-  internal static T GetOptionalPropertyParseable<T>(this JsonElement element, string propertyName, T defaultValue) where T : IParsable<T>
+  internal static Optional<T> GetOptionalPropertyParseable<T>(this JsonElement element, string propertyName) where T : IParsable<T>
   {
     if (!element.TryGetProperty(propertyName, out var property))
-      return defaultValue;
+      return Optional<T>.Empty;
 
     return T.Parse(property.GetString()!, CultureInfo.InvariantCulture);
   }
 
-  internal static T GetOptionalPropertyParseable<T>(this JsonElement element, string propertyName, Func<string, T> parser, T defaultValue)
+  internal static Optional<T> GetOptionalPropertyParseable<T>(this JsonElement element, string propertyName, Func<string, T> parser)
   {
     if (!element.TryGetProperty(propertyName, out var property))
-      return defaultValue;
+      return Optional<T>.Empty;
 
     return parser(property.GetString()!);
   }
@@ -88,10 +88,10 @@ internal static class ExtensionsJsonElement
     return parser(property);
   }
 
-  internal static T GetOptionalPropertyCustom<T>(this JsonElement element, string propertyName, Func<JsonElement, T> parser, T defaultValue)
+  internal static Optional<T> GetOptionalPropertyCustom<T>(this JsonElement element, string propertyName, Func<JsonElement, T> parser)
   {
     if (!element.TryGetProperty(propertyName, out var property))
-      return defaultValue;
+      return Optional<T>.Empty;
 
     return parser(property);
   }
diff --git a/src/DotTiled/Serialization/Tmj/TmjReaderBase.Data.cs b/src/DotTiled/Serialization/Tmj/TmjReaderBase.Data.cs
index 76945ca..f42ddd5 100644
--- a/src/DotTiled/Serialization/Tmj/TmjReaderBase.Data.cs
+++ b/src/DotTiled/Serialization/Tmj/TmjReaderBase.Data.cs
@@ -6,7 +6,7 @@ namespace DotTiled.Serialization.Tmj;
 
 public abstract partial class TmjReaderBase
 {
-  internal static Data ReadDataAsChunks(JsonElement element, DataCompression? compression, DataEncoding encoding)
+  internal static Data ReadDataAsChunks(JsonElement element, Optional<DataCompression> compression, DataEncoding encoding)
   {
     var chunks = element.GetValueAsList<Chunk>(e => ReadChunk(e, compression, encoding)).ToArray();
     return new Data
@@ -19,7 +19,7 @@ public abstract partial class TmjReaderBase
     };
   }
 
-  internal static Chunk ReadChunk(JsonElement element, DataCompression? compression, DataEncoding encoding)
+  internal static Chunk ReadChunk(JsonElement element, Optional<DataCompression> compression, DataEncoding encoding)
   {
     var data = ReadDataWithoutChunks(element, compression, encoding);
 
@@ -39,7 +39,7 @@ public abstract partial class TmjReaderBase
     };
   }
 
-  internal static Data ReadDataWithoutChunks(JsonElement element, DataCompression? compression, DataEncoding encoding)
+  internal static Data ReadDataWithoutChunks(JsonElement element, Optional<DataCompression> compression, DataEncoding encoding)
   {
     if (encoding == DataEncoding.Csv)
     {
@@ -52,7 +52,7 @@ public abstract partial class TmjReaderBase
     {
       var base64Data = element.GetBytesFromBase64();
 
-      if (compression == null)
+      if (!compression.HasValue)
       {
         var data = Helpers.ReadBytesAsInt32Array(base64Data);
         var (globalTileIDs, flippingFlags) = Helpers.ReadAndClearFlippingFlagsFromGIDs(data);
@@ -60,7 +60,7 @@ public abstract partial class TmjReaderBase
       }
 
       using var stream = new MemoryStream(base64Data);
-      var decompressed = compression switch
+      var decompressed = compression.Value switch
       {
         DataCompression.GZip => Helpers.DecompressGZip(stream),
         DataCompression.ZLib => Helpers.DecompressZLib(stream),
diff --git a/src/DotTiled/Serialization/Tmj/TmjReaderBase.Group.cs b/src/DotTiled/Serialization/Tmj/TmjReaderBase.Group.cs
index ca08df8..9548f1c 100644
--- a/src/DotTiled/Serialization/Tmj/TmjReaderBase.Group.cs
+++ b/src/DotTiled/Serialization/Tmj/TmjReaderBase.Group.cs
@@ -1,5 +1,4 @@
 using System.Collections.Generic;
-using System.Globalization;
 using System.Text.Json;
 
 namespace DotTiled.Serialization.Tmj;
@@ -10,16 +9,16 @@ public abstract partial class TmjReaderBase
   {
     var id = element.GetRequiredProperty<uint>("id");
     var name = element.GetRequiredProperty<string>("name");
-    var @class = element.GetOptionalProperty<string>("class", "");
-    var opacity = element.GetOptionalProperty<float>("opacity", 1.0f);
-    var visible = element.GetOptionalProperty<bool>("visible", true);
-    var tintColor = element.GetOptionalPropertyParseable<Color?>("tintcolor", s => Color.Parse(s, CultureInfo.InvariantCulture), null);
-    var offsetX = element.GetOptionalProperty<float>("offsetx", 0.0f);
-    var offsetY = element.GetOptionalProperty<float>("offsety", 0.0f);
-    var parallaxX = element.GetOptionalProperty<float>("parallaxx", 1.0f);
-    var parallaxY = element.GetOptionalProperty<float>("parallaxy", 1.0f);
-    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties, []);
-    var layers = element.GetOptionalPropertyCustom<List<BaseLayer>>("layers", e => e.GetValueAsList<BaseLayer>(ReadLayer), []);
+    var @class = element.GetOptionalProperty<string>("class").GetValueOr("");
+    var opacity = element.GetOptionalProperty<float>("opacity").GetValueOr(1.0f);
+    var visible = element.GetOptionalProperty<bool>("visible").GetValueOr(true);
+    var tintColor = element.GetOptionalPropertyParseable<Color>("tintcolor");
+    var offsetX = element.GetOptionalProperty<float>("offsetx").GetValueOr(0.0f);
+    var offsetY = element.GetOptionalProperty<float>("offsety").GetValueOr(0.0f);
+    var parallaxX = element.GetOptionalProperty<float>("parallaxx").GetValueOr(1.0f);
+    var parallaxY = element.GetOptionalProperty<float>("parallaxy").GetValueOr(1.0f);
+    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties).GetValueOr([]);
+    var layers = element.GetOptionalPropertyCustom<List<BaseLayer>>("layers", e => e.GetValueAsList<BaseLayer>(ReadLayer)).GetValueOr([]);
 
     return new Group
     {
diff --git a/src/DotTiled/Serialization/Tmj/TmjReaderBase.ImageLayer.cs b/src/DotTiled/Serialization/Tmj/TmjReaderBase.ImageLayer.cs
index f115a52..7034663 100644
--- a/src/DotTiled/Serialization/Tmj/TmjReaderBase.ImageLayer.cs
+++ b/src/DotTiled/Serialization/Tmj/TmjReaderBase.ImageLayer.cs
@@ -1,4 +1,3 @@
-using System.Globalization;
 using System.Text.Json;
 
 namespace DotTiled.Serialization.Tmj;
@@ -9,22 +8,22 @@ public abstract partial class TmjReaderBase
   {
     var id = element.GetRequiredProperty<uint>("id");
     var name = element.GetRequiredProperty<string>("name");
-    var @class = element.GetOptionalProperty<string>("class", "");
-    var opacity = element.GetOptionalProperty<float>("opacity", 1.0f);
-    var visible = element.GetOptionalProperty<bool>("visible", true);
-    var tintColor = element.GetOptionalPropertyParseable<Color?>("tintcolor", s => Color.Parse(s, CultureInfo.InvariantCulture), null);
-    var offsetX = element.GetOptionalProperty<float>("offsetx", 0.0f);
-    var offsetY = element.GetOptionalProperty<float>("offsety", 0.0f);
-    var parallaxX = element.GetOptionalProperty<float>("parallaxx", 1.0f);
-    var parallaxY = element.GetOptionalProperty<float>("parallaxy", 1.0f);
-    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties, []);
+    var @class = element.GetOptionalProperty<string>("class").GetValueOr("");
+    var opacity = element.GetOptionalProperty<float>("opacity").GetValueOr(1.0f);
+    var visible = element.GetOptionalProperty<bool>("visible").GetValueOr(true);
+    var tintColor = element.GetOptionalPropertyParseable<Color>("tintcolor");
+    var offsetX = element.GetOptionalProperty<float>("offsetx").GetValueOr(0.0f);
+    var offsetY = element.GetOptionalProperty<float>("offsety").GetValueOr(0.0f);
+    var parallaxX = element.GetOptionalProperty<float>("parallaxx").GetValueOr(1.0f);
+    var parallaxY = element.GetOptionalProperty<float>("parallaxy").GetValueOr(1.0f);
+    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties).GetValueOr([]);
 
     var image = element.GetRequiredProperty<string>("image");
-    var repeatX = element.GetOptionalProperty<bool>("repeatx", false);
-    var repeatY = element.GetOptionalProperty<bool>("repeaty", false);
-    var transparentColor = element.GetOptionalPropertyParseable<Color?>("transparentcolor", s => Color.Parse(s, CultureInfo.InvariantCulture), null);
-    var x = element.GetOptionalProperty<uint>("x", 0);
-    var y = element.GetOptionalProperty<uint>("y", 0);
+    var repeatX = element.GetOptionalProperty<bool>("repeatx").GetValueOr(false);
+    var repeatY = element.GetOptionalProperty<bool>("repeaty").GetValueOr(false);
+    var transparentColor = element.GetOptionalPropertyParseable<Color>("transparentcolor");
+    var x = element.GetOptionalProperty<uint>("x").GetValueOr(0);
+    var y = element.GetOptionalProperty<uint>("y").GetValueOr(0);
 
     var imgModel = new Image
     {
diff --git a/src/DotTiled/Serialization/Tmj/TmjReaderBase.Map.cs b/src/DotTiled/Serialization/Tmj/TmjReaderBase.Map.cs
index ec45b8d..eaa0a9e 100644
--- a/src/DotTiled/Serialization/Tmj/TmjReaderBase.Map.cs
+++ b/src/DotTiled/Serialization/Tmj/TmjReaderBase.Map.cs
@@ -10,7 +10,7 @@ public abstract partial class TmjReaderBase
   {
     var version = element.GetRequiredProperty<string>("version");
     var tiledVersion = element.GetRequiredProperty<string>("tiledversion");
-    string @class = element.GetOptionalProperty<string>("class", "");
+    var @class = element.GetOptionalProperty<string>("class").GetValueOr("");
     var orientation = element.GetRequiredPropertyParseable<MapOrientation>("orientation", s => s switch
     {
       "orthogonal" => MapOrientation.Orthogonal,
@@ -26,36 +26,36 @@ public abstract partial class TmjReaderBase
       "left-down" => RenderOrder.LeftDown,
       "left-up" => RenderOrder.LeftUp,
       _ => throw new JsonException($"Unknown render order '{s}'")
-    }, RenderOrder.RightDown);
-    var compressionLevel = element.GetOptionalProperty<int>("compressionlevel", -1);
+    }).GetValueOr(RenderOrder.RightDown);
+    var compressionLevel = element.GetOptionalProperty<int>("compressionlevel").GetValueOr(-1);
     var width = element.GetRequiredProperty<uint>("width");
     var height = element.GetRequiredProperty<uint>("height");
     var tileWidth = element.GetRequiredProperty<uint>("tilewidth");
     var tileHeight = element.GetRequiredProperty<uint>("tileheight");
-    var hexSideLength = element.GetOptionalProperty<uint?>("hexsidelength", null);
-    var staggerAxis = element.GetOptionalPropertyParseable<StaggerAxis?>("staggeraxis", s => s switch
+    var hexSideLength = element.GetOptionalProperty<uint>("hexsidelength");
+    var staggerAxis = element.GetOptionalPropertyParseable<StaggerAxis>("staggeraxis", s => s switch
     {
       "x" => StaggerAxis.X,
       "y" => StaggerAxis.Y,
       _ => throw new JsonException($"Unknown stagger axis '{s}'")
-    }, null);
-    var staggerIndex = element.GetOptionalPropertyParseable<StaggerIndex?>("staggerindex", s => s switch
+    });
+    var staggerIndex = element.GetOptionalPropertyParseable<StaggerIndex>("staggerindex", s => s switch
     {
       "odd" => StaggerIndex.Odd,
       "even" => StaggerIndex.Even,
       _ => throw new JsonException($"Unknown stagger index '{s}'")
-    }, null);
-    var parallaxOriginX = element.GetOptionalProperty<float>("parallaxoriginx", 0.0f);
-    var parallaxOriginY = element.GetOptionalProperty<float>("parallaxoriginy", 0.0f);
-    var backgroundColor = element.GetOptionalPropertyParseable<Color>("backgroundcolor", s => Color.Parse(s, CultureInfo.InvariantCulture), Color.Parse("#00000000", CultureInfo.InvariantCulture));
+    });
+    var parallaxOriginX = element.GetOptionalProperty<float>("parallaxoriginx").GetValueOr(0f);
+    var parallaxOriginY = element.GetOptionalProperty<float>("parallaxoriginy").GetValueOr(0f);
+    var backgroundColor = element.GetOptionalPropertyParseable<Color>("backgroundcolor").GetValueOr(Color.Parse("#00000000", CultureInfo.InvariantCulture));
     var nextLayerID = element.GetRequiredProperty<uint>("nextlayerid");
     var nextObjectID = element.GetRequiredProperty<uint>("nextobjectid");
-    var infinite = element.GetOptionalProperty<bool>("infinite", false);
+    var infinite = element.GetOptionalProperty<bool>("infinite").GetValueOr(false);
 
-    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties, []);
+    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties).GetValueOr([]);
 
-    List<BaseLayer> layers = element.GetOptionalPropertyCustom<List<BaseLayer>>("layers", e => e.GetValueAsList<BaseLayer>(el => ReadLayer(el)), []);
-    List<Tileset> tilesets = element.GetOptionalPropertyCustom<List<Tileset>>("tilesets", e => e.GetValueAsList<Tileset>(el => ReadTileset(el)), []);
+    List<BaseLayer> layers = element.GetOptionalPropertyCustom<List<BaseLayer>>("layers", e => e.GetValueAsList<BaseLayer>(el => ReadLayer(el))).GetValueOr([]);
+    List<Tileset> tilesets = element.GetOptionalPropertyCustom<List<Tileset>>("tilesets", e => e.GetValueAsList<Tileset>(el => ReadTileset(el, version, tiledVersion))).GetValueOr([]);
 
     return new Map
     {
diff --git a/src/DotTiled/Serialization/Tmj/TmjReaderBase.ObjectLayer.cs b/src/DotTiled/Serialization/Tmj/TmjReaderBase.ObjectLayer.cs
index 1b8ef23..0456157 100644
--- a/src/DotTiled/Serialization/Tmj/TmjReaderBase.ObjectLayer.cs
+++ b/src/DotTiled/Serialization/Tmj/TmjReaderBase.ObjectLayer.cs
@@ -11,29 +11,29 @@ public abstract partial class TmjReaderBase
   {
     var id = element.GetRequiredProperty<uint>("id");
     var name = element.GetRequiredProperty<string>("name");
-    var @class = element.GetOptionalProperty<string>("class", "");
-    var opacity = element.GetOptionalProperty<float>("opacity", 1.0f);
-    var visible = element.GetOptionalProperty<bool>("visible", true);
-    var tintColor = element.GetOptionalPropertyParseable<Color?>("tintcolor", s => Color.Parse(s, CultureInfo.InvariantCulture), null);
-    var offsetX = element.GetOptionalProperty<float>("offsetx", 0.0f);
-    var offsetY = element.GetOptionalProperty<float>("offsety", 0.0f);
-    var parallaxX = element.GetOptionalProperty<float>("parallaxx", 1.0f);
-    var parallaxY = element.GetOptionalProperty<float>("parallaxy", 1.0f);
-    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties, []);
+    var @class = element.GetOptionalProperty<string>("class").GetValueOr("");
+    var opacity = element.GetOptionalProperty<float>("opacity").GetValueOr(1.0f);
+    var visible = element.GetOptionalProperty<bool>("visible").GetValueOr(true);
+    var tintColor = element.GetOptionalPropertyParseable<Color>("tintcolor");
+    var offsetX = element.GetOptionalProperty<float>("offsetx").GetValueOr(0.0f);
+    var offsetY = element.GetOptionalProperty<float>("offsety").GetValueOr(0.0f);
+    var parallaxX = element.GetOptionalProperty<float>("parallaxx").GetValueOr(1.0f);
+    var parallaxY = element.GetOptionalProperty<float>("parallaxy").GetValueOr(1.0f);
+    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties).GetValueOr([]);
 
-    var x = element.GetOptionalProperty<uint>("x", 0);
-    var y = element.GetOptionalProperty<uint>("y", 0);
-    var width = element.GetOptionalProperty<uint?>("width", null);
-    var height = element.GetOptionalProperty<uint?>("height", null);
-    var color = element.GetOptionalPropertyParseable<Color?>("color", s => Color.Parse(s, CultureInfo.InvariantCulture), null);
+    var x = element.GetOptionalProperty<uint>("x").GetValueOr(0);
+    var y = element.GetOptionalProperty<uint>("y").GetValueOr(0);
+    var width = element.GetOptionalProperty<uint>("width").GetValueOr(0);
+    var height = element.GetOptionalProperty<uint>("height").GetValueOr(0);
+    var color = element.GetOptionalPropertyParseable<Color>("color");
     var drawOrder = element.GetOptionalPropertyParseable<DrawOrder>("draworder", s => s switch
     {
       "topdown" => DrawOrder.TopDown,
       "index" => DrawOrder.Index,
       _ => throw new JsonException($"Unknown draw order '{s}'.")
-    }, DrawOrder.TopDown);
+    }).GetValueOr(DrawOrder.TopDown);
 
-    var objects = element.GetOptionalPropertyCustom<List<DotTiled.Object>>("objects", e => e.GetValueAsList<DotTiled.Object>(el => ReadObject(el)), []);
+    var objects = element.GetOptionalPropertyCustom<List<DotTiled.Object>>("objects", e => e.GetValueAsList<DotTiled.Object>(el => ReadObject(el))).GetValueOr([]);
 
     return new ObjectLayer
     {
@@ -50,8 +50,8 @@ public abstract partial class TmjReaderBase
       Properties = properties,
       X = x,
       Y = y,
-      Width = width ?? 0,
-      Height = height ?? 0,
+      Width = width,
+      Height = height,
       Color = color,
       DrawOrder = drawOrder,
       Objects = objects
@@ -60,7 +60,7 @@ public abstract partial class TmjReaderBase
 
   internal DotTiled.Object ReadObject(JsonElement element)
   {
-    uint? idDefault = null;
+    Optional<uint> idDefault = Optional<uint>.Empty;
     string nameDefault = "";
     string typeDefault = "";
     float xDefault = 0f;
@@ -68,16 +68,16 @@ public abstract partial class TmjReaderBase
     float widthDefault = 0f;
     float heightDefault = 0f;
     float rotationDefault = 0f;
-    uint? gidDefault = null;
     bool visibleDefault = true;
     bool ellipseDefault = false;
     bool pointDefault = false;
-    List<Vector2>? polygonDefault = null;
-    List<Vector2>? polylineDefault = null;
+
+    List<Vector2> polygonDefault = null;
+    List<Vector2> polylineDefault = null;
     List<IProperty> propertiesDefault = [];
 
-    var template = element.GetOptionalProperty<string?>("template", null);
-    if (template is not null)
+    var template = element.GetOptionalProperty<string>("template");
+    if (template.HasValue)
     {
       var resolvedTemplate = _externalTemplateResolver(template);
       var templObj = resolvedTemplate.Object;
@@ -98,24 +98,24 @@ public abstract partial class TmjReaderBase
       polylineDefault = (templObj is PolylineObject polylineObj) ? polylineObj.Points : null;
     }
 
-    var ellipse = element.GetOptionalProperty<bool>("ellipse", ellipseDefault);
-    var gid = element.GetOptionalProperty<uint?>("gid", gidDefault);
-    var height = element.GetOptionalProperty<float>("height", heightDefault);
-    var id = element.GetOptionalProperty<uint?>("id", idDefault);
-    var name = element.GetOptionalProperty<string>("name", nameDefault);
-    var point = element.GetOptionalProperty<bool>("point", pointDefault);
-    var polygon = element.GetOptionalPropertyCustom<List<Vector2>?>("polygon", ReadPoints, polygonDefault);
-    var polyline = element.GetOptionalPropertyCustom<List<Vector2>?>("polyline", ReadPoints, polylineDefault);
-    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties, propertiesDefault);
-    var rotation = element.GetOptionalProperty<float>("rotation", rotationDefault);
-    var text = element.GetOptionalPropertyCustom<TextObject?>("text", ReadText, null);
-    var type = element.GetOptionalProperty<string>("type", typeDefault);
-    var visible = element.GetOptionalProperty<bool>("visible", visibleDefault);
-    var width = element.GetOptionalProperty<float>("width", widthDefault);
-    var x = element.GetOptionalProperty<float>("x", xDefault);
-    var y = element.GetOptionalProperty<float>("y", yDefault);
+    var ellipse = element.GetOptionalProperty<bool>("ellipse").GetValueOr(ellipseDefault);
+    var gid = element.GetOptionalProperty<uint>("gid");
+    var height = element.GetOptionalProperty<float>("height").GetValueOr(heightDefault);
+    var id = element.GetOptionalProperty<uint>("id").GetValueOrOptional(idDefault);
+    var name = element.GetOptionalProperty<string>("name").GetValueOr(nameDefault);
+    var point = element.GetOptionalProperty<bool>("point").GetValueOr(pointDefault);
+    var polygon = element.GetOptionalPropertyCustom<List<Vector2>>("polygon", ReadPoints).GetValueOr(polygonDefault);
+    var polyline = element.GetOptionalPropertyCustom<List<Vector2>>("polyline", ReadPoints).GetValueOr(polylineDefault);
+    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties).GetValueOr(propertiesDefault);
+    var rotation = element.GetOptionalProperty<float>("rotation").GetValueOr(rotationDefault);
+    var text = element.GetOptionalPropertyCustom<TextObject>("text", ReadText);
+    var type = element.GetOptionalProperty<string>("type").GetValueOr(typeDefault);
+    var visible = element.GetOptionalProperty<bool>("visible").GetValueOr(visibleDefault);
+    var width = element.GetOptionalProperty<float>("width").GetValueOr(widthDefault);
+    var x = element.GetOptionalProperty<float>("x").GetValueOr(xDefault);
+    var y = element.GetOptionalProperty<float>("y").GetValueOr(yDefault);
 
-    if (gid is not null)
+    if (gid.HasValue)
     {
       return new TileObject
       {
@@ -208,19 +208,19 @@ public abstract partial class TmjReaderBase
       };
     }
 
-    if (text is not null)
+    if (text.HasValue)
     {
-      text.ID = id;
-      text.Name = name;
-      text.Type = type;
-      text.X = x;
-      text.Y = y;
-      text.Width = width;
-      text.Height = height;
-      text.Rotation = rotation;
-      text.Visible = visible;
-      text.Template = template;
-      text.Properties = properties;
+      text.Value.ID = id;
+      text.Value.Name = name;
+      text.Value.Type = type;
+      text.Value.X = x;
+      text.Value.Y = y;
+      text.Value.Width = width;
+      text.Value.Height = height;
+      text.Value.Rotation = rotation;
+      text.Value.Visible = visible;
+      text.Value.Template = template;
+      text.Value.Properties = properties;
       return text;
     }
 
@@ -250,30 +250,30 @@ public abstract partial class TmjReaderBase
 
   internal static TextObject ReadText(JsonElement element)
   {
-    var bold = element.GetOptionalProperty<bool>("bold", false);
-    var color = element.GetOptionalPropertyParseable<Color>("color", s => Color.Parse(s, CultureInfo.InvariantCulture), Color.Parse("#00000000", CultureInfo.InvariantCulture));
-    var fontfamily = element.GetOptionalProperty<string>("fontfamily", "sans-serif");
+    var bold = element.GetOptionalProperty<bool>("bold").GetValueOr(false);
+    var color = element.GetOptionalPropertyParseable<Color>("color").GetValueOr(Color.Parse("#00000000", CultureInfo.InvariantCulture));
+    var fontfamily = element.GetOptionalProperty<string>("fontfamily").GetValueOr("sans-serif");
     var halign = element.GetOptionalPropertyParseable<TextHorizontalAlignment>("halign", s => s switch
     {
       "left" => TextHorizontalAlignment.Left,
       "center" => TextHorizontalAlignment.Center,
       "right" => TextHorizontalAlignment.Right,
       _ => throw new JsonException($"Unknown horizontal alignment '{s}'.")
-    }, TextHorizontalAlignment.Left);
-    var italic = element.GetOptionalProperty<bool>("italic", false);
-    var kerning = element.GetOptionalProperty<bool>("kerning", true);
-    var pixelsize = element.GetOptionalProperty<int>("pixelsize", 16);
-    var strikeout = element.GetOptionalProperty<bool>("strikeout", false);
+    }).GetValueOr(TextHorizontalAlignment.Left);
+    var italic = element.GetOptionalProperty<bool>("italic").GetValueOr(false);
+    var kerning = element.GetOptionalProperty<bool>("kerning").GetValueOr(true);
+    var pixelsize = element.GetOptionalProperty<int>("pixelsize").GetValueOr(16);
+    var strikeout = element.GetOptionalProperty<bool>("strikeout").GetValueOr(false);
     var text = element.GetRequiredProperty<string>("text");
-    var underline = element.GetOptionalProperty<bool>("underline", false);
+    var underline = element.GetOptionalProperty<bool>("underline").GetValueOr(false);
     var valign = element.GetOptionalPropertyParseable<TextVerticalAlignment>("valign", s => s switch
     {
       "top" => TextVerticalAlignment.Top,
       "center" => TextVerticalAlignment.Center,
       "bottom" => TextVerticalAlignment.Bottom,
       _ => throw new JsonException($"Unknown vertical alignment '{s}'.")
-    }, TextVerticalAlignment.Top);
-    var wrap = element.GetOptionalProperty<bool>("wrap", false);
+    }).GetValueOr(TextVerticalAlignment.Top);
+    var wrap = element.GetOptionalProperty<bool>("wrap").GetValueOr(false);
 
     return new TextObject
     {
diff --git a/src/DotTiled/Serialization/Tmj/TmjReaderBase.Properties.cs b/src/DotTiled/Serialization/Tmj/TmjReaderBase.Properties.cs
index c8683b2..b877382 100644
--- a/src/DotTiled/Serialization/Tmj/TmjReaderBase.Properties.cs
+++ b/src/DotTiled/Serialization/Tmj/TmjReaderBase.Properties.cs
@@ -22,9 +22,9 @@ public abstract partial class TmjReaderBase
         "object" => PropertyType.Object,
         "class" => PropertyType.Class,
         _ => throw new JsonException("Invalid property type")
-      }, PropertyType.String);
-      var propertyType = e.GetOptionalProperty<string?>("propertytype", null);
-      if (propertyType is not null)
+      }).GetValueOr(PropertyType.String);
+      var propertyType = e.GetOptionalProperty<string>("propertytype");
+      if (propertyType.HasValue)
       {
         return ReadPropertyWithCustomType(e);
       }
@@ -48,7 +48,7 @@ public abstract partial class TmjReaderBase
 
   internal IProperty ReadPropertyWithCustomType(JsonElement element)
   {
-    var isClass = element.GetOptionalProperty<string?>("type", null) == "class";
+    var isClass = element.GetOptionalProperty<string>("type") == "class";
     if (isClass)
     {
       return ReadClassProperty(element);
@@ -66,7 +66,7 @@ public abstract partial class TmjReaderBase
     if (customTypeDef is CustomClassDefinition ccd)
     {
       var propsInType = Helpers.CreateInstanceOfCustomClass(ccd, _customTypeResolver);
-      var props = element.GetOptionalPropertyCustom<List<IProperty>>("value", e => ReadPropertiesInsideClass(e, ccd), []);
+      var props = element.GetOptionalPropertyCustom<List<IProperty>>("value", e => ReadPropertiesInsideClass(e, ccd)).GetValueOr([]);
       var mergedProps = Helpers.MergeProperties(propsInType, props);
 
       return new ClassProperty
@@ -120,7 +120,7 @@ public abstract partial class TmjReaderBase
       "string" => PropertyType.String,
       "int" => PropertyType.Int,
       _ => throw new JsonException("Invalid property type")
-    }, PropertyType.String);
+    }).GetValueOr(PropertyType.String);
     var customTypeDef = _customTypeResolver(propertyType);
 
     if (customTypeDef is not CustomEnumDefinition ced)
diff --git a/src/DotTiled/Serialization/Tmj/TmjReaderBase.Template.cs b/src/DotTiled/Serialization/Tmj/TmjReaderBase.Template.cs
index 88bcf09..1bda13a 100644
--- a/src/DotTiled/Serialization/Tmj/TmjReaderBase.Template.cs
+++ b/src/DotTiled/Serialization/Tmj/TmjReaderBase.Template.cs
@@ -7,7 +7,7 @@ public abstract partial class TmjReaderBase
   internal Template ReadTemplate(JsonElement element)
   {
     var type = element.GetRequiredProperty<string>("type");
-    var tileset = element.GetOptionalPropertyCustom<Tileset?>("tileset", ReadTileset, null);
+    var tileset = element.GetOptionalPropertyCustom<Tileset>("tileset", e => ReadTileset(e));
     var @object = element.GetRequiredPropertyCustom<DotTiled.Object>("object", ReadObject);
 
     return new Template
diff --git a/src/DotTiled/Serialization/Tmj/TmjReaderBase.TileLayer.cs b/src/DotTiled/Serialization/Tmj/TmjReaderBase.TileLayer.cs
index e3ccc9a..7c8791a 100644
--- a/src/DotTiled/Serialization/Tmj/TmjReaderBase.TileLayer.cs
+++ b/src/DotTiled/Serialization/Tmj/TmjReaderBase.TileLayer.cs
@@ -1,4 +1,3 @@
-using System.Globalization;
 using System.Text.Json;
 
 namespace DotTiled.Serialization.Tmj;
@@ -7,43 +6,43 @@ public abstract partial class TmjReaderBase
 {
   internal TileLayer ReadTileLayer(JsonElement element)
   {
-    var compression = element.GetOptionalPropertyParseable<DataCompression?>("compression", s => s switch
-    {
-      "zlib" => DataCompression.ZLib,
-      "gzip" => DataCompression.GZip,
-      "" => null,
-      _ => throw new JsonException($"Unsupported compression '{s}'.")
-    }, null);
     var encoding = element.GetOptionalPropertyParseable<DataEncoding>("encoding", s => s switch
     {
       "csv" => DataEncoding.Csv,
       "base64" => DataEncoding.Base64,
       _ => throw new JsonException($"Unsupported encoding '{s}'.")
-    }, DataEncoding.Csv);
-    var chunks = element.GetOptionalPropertyCustom<Data?>("chunks", e => ReadDataAsChunks(e, compression, encoding), null);
-    var @class = element.GetOptionalProperty<string>("class", "");
-    var data = element.GetOptionalPropertyCustom<Data?>("data", e => ReadDataWithoutChunks(e, compression, encoding), null);
+    }).GetValueOr(DataEncoding.Csv);
+    var compression = element.GetOptionalPropertyParseable<DataCompression>("compression", s => s switch
+    {
+      "zlib" => DataCompression.ZLib,
+      "gzip" => DataCompression.GZip,
+      "" => Optional<DataCompression>.Empty,
+      _ => throw new JsonException($"Unsupported compression '{s}'.")
+    });
+    var chunks = element.GetOptionalPropertyCustom<Data>("chunks", e => ReadDataAsChunks(e, compression, encoding));
+    var @class = element.GetOptionalProperty<string>("class").GetValueOr("");
+    var data = element.GetOptionalPropertyCustom<Data>("data", e => ReadDataWithoutChunks(e, compression, encoding));
     var height = element.GetRequiredProperty<uint>("height");
     var id = element.GetRequiredProperty<uint>("id");
     var name = element.GetRequiredProperty<string>("name");
-    var offsetX = element.GetOptionalProperty<float>("offsetx", 0.0f);
-    var offsetY = element.GetOptionalProperty<float>("offsety", 0.0f);
-    var opacity = element.GetOptionalProperty<float>("opacity", 1.0f);
-    var parallaxx = element.GetOptionalProperty<float>("parallaxx", 1.0f);
-    var parallaxy = element.GetOptionalProperty<float>("parallaxy", 1.0f);
-    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties, []);
-    var repeatX = element.GetOptionalProperty<bool>("repeatx", false);
-    var repeatY = element.GetOptionalProperty<bool>("repeaty", false);
-    var startX = element.GetOptionalProperty<int>("startx", 0);
-    var startY = element.GetOptionalProperty<int>("starty", 0);
-    var tintColor = element.GetOptionalPropertyParseable<Color?>("tintcolor", s => Color.Parse(s, CultureInfo.InvariantCulture), null);
-    var transparentColor = element.GetOptionalPropertyParseable<Color?>("transparentcolor", s => Color.Parse(s, CultureInfo.InvariantCulture), null);
-    var visible = element.GetOptionalProperty<bool>("visible", true);
+    var offsetX = element.GetOptionalProperty<float>("offsetx").GetValueOr(0.0f);
+    var offsetY = element.GetOptionalProperty<float>("offsety").GetValueOr(0.0f);
+    var opacity = element.GetOptionalProperty<float>("opacity").GetValueOr(1.0f);
+    var parallaxx = element.GetOptionalProperty<float>("parallaxx").GetValueOr(1.0f);
+    var parallaxy = element.GetOptionalProperty<float>("parallaxy").GetValueOr(1.0f);
+    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties).GetValueOr([]);
+    var repeatX = element.GetOptionalProperty<bool>("repeatx").GetValueOr(false);
+    var repeatY = element.GetOptionalProperty<bool>("repeaty").GetValueOr(false);
+    var startX = element.GetOptionalProperty<int>("startx").GetValueOr(0);
+    var startY = element.GetOptionalProperty<int>("starty").GetValueOr(0);
+    var tintColor = element.GetOptionalPropertyParseable<Color>("tintcolor");
+    var transparentColor = element.GetOptionalPropertyParseable<Color>("transparentcolor");
+    var visible = element.GetOptionalProperty<bool>("visible").GetValueOr(true);
     var width = element.GetRequiredProperty<uint>("width");
     var x = element.GetRequiredProperty<uint>("x");
     var y = element.GetRequiredProperty<uint>("y");
 
-    if ((data ?? chunks) is null)
+    if (!data.HasValue && !chunks.HasValue)
       throw new JsonException("Tile layer does not contain data.");
 
     return new TileLayer
diff --git a/src/DotTiled/Serialization/Tmj/TmjReaderBase.Tileset.cs b/src/DotTiled/Serialization/Tmj/TmjReaderBase.Tileset.cs
index 8a41117..ea91acf 100644
--- a/src/DotTiled/Serialization/Tmj/TmjReaderBase.Tileset.cs
+++ b/src/DotTiled/Serialization/Tmj/TmjReaderBase.Tileset.cs
@@ -1,29 +1,31 @@
 using System.Collections.Generic;
-using System.Globalization;
 using System.Text.Json;
 
 namespace DotTiled.Serialization.Tmj;
 
 public abstract partial class TmjReaderBase
 {
-  internal Tileset ReadTileset(JsonElement element)
+  internal Tileset ReadTileset(
+    JsonElement element,
+    Optional<string> parentVersion = null,
+    Optional<string> parentTiledVersion = null)
   {
-    var backgroundColor = element.GetOptionalPropertyParseable<Color?>("backgroundcolor", s => Color.Parse(s, CultureInfo.InvariantCulture), null);
-    var @class = element.GetOptionalProperty<string>("class", "");
-    var columns = element.GetOptionalProperty<uint?>("columns", null);
+    var backgroundColor = element.GetOptionalPropertyParseable<Color>("backgroundcolor");
+    var @class = element.GetOptionalProperty<string>("class").GetValueOr("");
+    var columns = element.GetOptionalProperty<uint>("columns");
     var fillMode = element.GetOptionalPropertyParseable<FillMode>("fillmode", s => s switch
     {
       "stretch" => FillMode.Stretch,
       "preserve-aspect-fit" => FillMode.PreserveAspectFit,
       _ => throw new JsonException($"Unknown fill mode '{s}'")
-    }, FillMode.Stretch);
-    var firstGID = element.GetOptionalProperty<uint?>("firstgid", null);
-    var grid = element.GetOptionalPropertyCustom<Grid?>("grid", ReadGrid, null);
-    var image = element.GetOptionalProperty<string?>("image", null);
-    var imageHeight = element.GetOptionalProperty<uint?>("imageheight", null);
-    var imageWidth = element.GetOptionalProperty<uint?>("imagewidth", null);
-    var margin = element.GetOptionalProperty<uint?>("margin", null);
-    var name = element.GetOptionalProperty<string?>("name", null);
+    }).GetValueOr(FillMode.Stretch);
+    var firstGID = element.GetOptionalProperty<uint>("firstgid");
+    var grid = element.GetOptionalPropertyCustom<Grid>("grid", ReadGrid);
+    var image = element.GetOptionalProperty<string>("image");
+    var imageHeight = element.GetOptionalProperty<uint>("imageheight");
+    var imageWidth = element.GetOptionalProperty<uint>("imagewidth");
+    var margin = element.GetOptionalProperty<uint>("margin");
+    var name = element.GetOptionalProperty<string>("name");
     var objectAlignment = element.GetOptionalPropertyParseable<ObjectAlignment>("objectalignment", s => s switch
     {
       "unspecified" => ObjectAlignment.Unspecified,
@@ -37,29 +39,29 @@ public abstract partial class TmjReaderBase
       "bottom" => ObjectAlignment.Bottom,
       "bottomright" => ObjectAlignment.BottomRight,
       _ => throw new JsonException($"Unknown object alignment '{s}'")
-    }, ObjectAlignment.Unspecified);
-    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties, []);
-    var source = element.GetOptionalProperty<string?>("source", null);
-    var spacing = element.GetOptionalProperty<uint?>("spacing", null);
-    var tileCount = element.GetOptionalProperty<uint?>("tilecount", null);
-    var tiledVersion = element.GetOptionalProperty<string?>("tiledversion", null);
-    var tileHeight = element.GetOptionalProperty<uint?>("tileheight", null);
-    var tileOffset = element.GetOptionalPropertyCustom<TileOffset?>("tileoffset", ReadTileOffset, null);
+    }).GetValueOr(ObjectAlignment.Unspecified);
+    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties).GetValueOr([]);
+    var source = element.GetOptionalProperty<string>("source");
+    var spacing = element.GetOptionalProperty<uint>("spacing");
+    var tileCount = element.GetOptionalProperty<uint>("tilecount");
+    var tiledVersion = element.GetOptionalProperty<string>("tiledversion").GetValueOrOptional(parentTiledVersion);
+    var tileHeight = element.GetOptionalProperty<uint>("tileheight");
+    var tileOffset = element.GetOptionalPropertyCustom<TileOffset>("tileoffset", ReadTileOffset);
     var tileRenderSize = element.GetOptionalPropertyParseable<TileRenderSize>("tilerendersize", s => s switch
     {
       "tile" => TileRenderSize.Tile,
       "grid" => TileRenderSize.Grid,
       _ => throw new JsonException($"Unknown tile render size '{s}'")
-    }, TileRenderSize.Tile);
-    var tiles = element.GetOptionalPropertyCustom<List<Tile>>("tiles", ReadTiles, []);
-    var tileWidth = element.GetOptionalProperty<uint?>("tilewidth", null);
-    var transparentColor = element.GetOptionalPropertyParseable<Color?>("transparentcolor", s => Color.Parse(s, CultureInfo.InvariantCulture), null);
-    var type = element.GetOptionalProperty<string?>("type", null);
-    var version = element.GetOptionalProperty<string?>("version", null);
-    var transformations = element.GetOptionalPropertyCustom<Transformations?>("transformations", ReadTransformations, null);
-    var wangsets = element.GetOptionalPropertyCustom<List<Wangset>?>("wangsets", el => el.GetValueAsList<Wangset>(e => ReadWangset(e)), null);
+    }).GetValueOr(TileRenderSize.Tile);
+    var tiles = element.GetOptionalPropertyCustom<List<Tile>>("tiles", ReadTiles).GetValueOr([]);
+    var tileWidth = element.GetOptionalProperty<uint>("tilewidth");
+    var transparentColor = element.GetOptionalPropertyParseable<Color>("transparentcolor");
+    var type = element.GetOptionalProperty<string>("type");
+    var version = element.GetOptionalProperty<string>("version").GetValueOrOptional(parentVersion);
+    var transformations = element.GetOptionalPropertyCustom<Transformations>("transformations", ReadTransformations);
+    var wangsets = element.GetOptionalPropertyCustom<List<Wangset>>("wangsets", el => el.GetValueAsList<Wangset>(e => ReadWangset(e))).GetValueOr([]);
 
-    if (source is not null)
+    if (source.HasValue)
     {
       var resolvedTileset = _externalTilesetResolver(source);
       resolvedTileset.FirstGID = firstGID;
@@ -67,49 +69,48 @@ public abstract partial class TmjReaderBase
       return resolvedTileset;
     }
 
-    var imageModel = image is not null ? new Image
+    Optional<Image> imageModel = image.HasValue ? new Image
     {
       Format = Helpers.ParseImageFormatFromSource(image),
       Source = image,
       Height = imageHeight,
       Width = imageWidth,
       TransparentColor = transparentColor
-    } : null;
+    } : Optional<Image>.Empty;
 
-    return null;
-    // return new Tileset
-    // {
-    //   Class = @class,
-    //   Columns = columns,
-    //   FillMode = fillMode,
-    //   FirstGID = firstGID,
-    //   Grid = grid,
-    //   Image = imageModel,
-    //   Margin = margin,
-    //   Name = name,
-    //   ObjectAlignment = objectAlignment,
-    //   Properties = properties,
-    //   Source = source,
-    //   Spacing = spacing,
-    //   TileCount = tileCount,
-    //   TiledVersion = tiledVersion,
-    //   TileHeight = tileHeight,
-    //   TileOffset = tileOffset,
-    //   RenderSize = tileRenderSize,
-    //   Tiles = tiles,
-    //   TileWidth = tileWidth,
-    //   Version = version,
-    //   Wangsets = wangsets,
-    //   Transformations = transformations
-    // };
+    return new Tileset
+    {
+      Class = @class,
+      Columns = columns,
+      FillMode = fillMode,
+      FirstGID = firstGID,
+      Grid = grid,
+      Image = imageModel,
+      Margin = margin,
+      Name = name,
+      ObjectAlignment = objectAlignment,
+      Properties = properties,
+      Source = source,
+      Spacing = spacing,
+      TileCount = tileCount,
+      TiledVersion = tiledVersion,
+      TileHeight = tileHeight,
+      TileOffset = tileOffset,
+      RenderSize = tileRenderSize,
+      Tiles = tiles,
+      TileWidth = tileWidth,
+      Version = version,
+      Wangsets = wangsets,
+      Transformations = transformations
+    };
   }
 
   internal static Transformations ReadTransformations(JsonElement element)
   {
-    var hFlip = element.GetOptionalProperty<bool>("hflip", false);
-    var vFlip = element.GetOptionalProperty<bool>("vflip", false);
-    var rotate = element.GetOptionalProperty<bool>("rotate", false);
-    var preferUntransformed = element.GetOptionalProperty<bool>("preferuntransformed", false);
+    var hFlip = element.GetOptionalProperty<bool>("hflip").GetValueOr(false);
+    var vFlip = element.GetOptionalProperty<bool>("vflip").GetValueOr(false);
+    var rotate = element.GetOptionalProperty<bool>("rotate").GetValueOr(false);
+    var preferUntransformed = element.GetOptionalProperty<bool>("preferuntransformed").GetValueOr(false);
 
     return new Transformations
     {
@@ -127,7 +128,7 @@ public abstract partial class TmjReaderBase
       "orthogonal" => GridOrientation.Orthogonal,
       "isometric" => GridOrientation.Isometric,
       _ => throw new JsonException($"Unknown grid orientation '{s}'")
-    }, GridOrientation.Orthogonal);
+    }).GetValueOr(GridOrientation.Orthogonal);
     var height = element.GetRequiredProperty<uint>("height");
     var width = element.GetRequiredProperty<uint>("width");
 
@@ -154,28 +155,27 @@ public abstract partial class TmjReaderBase
   internal List<Tile> ReadTiles(JsonElement element) =>
     element.GetValueAsList<Tile>(e =>
     {
-      var animation = e.GetOptionalPropertyCustom<List<Frame>?>("animation", e => e.GetValueAsList<Frame>(ReadFrame), null);
+      var animation = e.GetOptionalPropertyCustom<List<Frame>>("animation", e => e.GetValueAsList<Frame>(ReadFrame)).GetValueOr([]);
       var id = e.GetRequiredProperty<uint>("id");
-      var image = e.GetOptionalProperty<string?>("image", null);
-      var imageHeight = e.GetOptionalProperty<uint?>("imageheight", null);
-      var imageWidth = e.GetOptionalProperty<uint?>("imagewidth", null);
-      var x = e.GetOptionalProperty<uint>("x", 0);
-      var y = e.GetOptionalProperty<uint>("y", 0);
-      var width = e.GetOptionalProperty<uint>("width", imageWidth ?? 0);
-      var height = e.GetOptionalProperty<uint>("height", imageHeight ?? 0);
-      var objectGroup = e.GetOptionalPropertyCustom<ObjectLayer?>("objectgroup", e => ReadObjectLayer(e), null);
-      var probability = e.GetOptionalProperty<float>("probability", 0.0f);
-      var properties = e.GetOptionalPropertyCustom("properties", ReadProperties, []);
-      // var terrain, replaced by wangsets
-      var type = e.GetOptionalProperty<string>("type", "");
+      var image = e.GetOptionalProperty<string>("image");
+      var imageHeight = e.GetOptionalProperty<uint>("imageheight");
+      var imageWidth = e.GetOptionalProperty<uint>("imagewidth");
+      var x = e.GetOptionalProperty<uint>("x").GetValueOr(0);
+      var y = e.GetOptionalProperty<uint>("y").GetValueOr(0);
+      var width = e.GetOptionalProperty<uint>("width").GetValueOr(imageWidth.GetValueOr(0));
+      var height = e.GetOptionalProperty<uint>("height").GetValueOr(imageHeight.GetValueOr(0));
+      var objectGroup = e.GetOptionalPropertyCustom<ObjectLayer>("objectgroup", e => ReadObjectLayer(e));
+      var probability = e.GetOptionalProperty<float>("probability").GetValueOr(0.0f);
+      var properties = e.GetOptionalPropertyCustom("properties", ReadProperties).GetValueOr([]);
+      var type = e.GetOptionalProperty<string>("type").GetValueOr("");
 
-      var imageModel = image != null ? new Image
+      Optional<Image> imageModel = image.HasValue ? new Image
       {
         Format = Helpers.ParseImageFormatFromSource(image),
         Source = image,
         Height = imageHeight ?? 0,
         Width = imageWidth ?? 0
-      } : null;
+      } : Optional<Image>.Empty;
 
       return new Tile
       {
@@ -207,13 +207,13 @@ public abstract partial class TmjReaderBase
 
   internal Wangset ReadWangset(JsonElement element)
   {
-    var @clalss = element.GetOptionalProperty<string>("class", "");
-    var colors = element.GetOptionalPropertyCustom<List<WangColor>>("colors", e => e.GetValueAsList<WangColor>(el => ReadWangColor(el)), []);
+    var @clalss = element.GetOptionalProperty<string>("class").GetValueOr("");
+    var colors = element.GetOptionalPropertyCustom<List<WangColor>>("colors", e => e.GetValueAsList<WangColor>(el => ReadWangColor(el))).GetValueOr([]);
     var name = element.GetRequiredProperty<string>("name");
-    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties, []);
-    var tile = element.GetOptionalProperty<int>("tile", 0);
-    var type = element.GetOptionalProperty<string>("type", "");
-    var wangTiles = element.GetOptionalPropertyCustom<List<WangTile>>("wangtiles", e => e.GetValueAsList<WangTile>(ReadWangTile), []);
+    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties).GetValueOr([]);
+    var tile = element.GetOptionalProperty<int>("tile").GetValueOr(0);
+    var type = element.GetOptionalProperty<string>("type").GetValueOr("");
+    var wangTiles = element.GetOptionalPropertyCustom<List<WangTile>>("wangtiles", e => e.GetValueAsList<WangTile>(ReadWangTile)).GetValueOr([]);
 
     return new Wangset
     {
@@ -228,12 +228,12 @@ public abstract partial class TmjReaderBase
 
   internal WangColor ReadWangColor(JsonElement element)
   {
-    var @class = element.GetOptionalProperty<string>("class", "");
-    var color = element.GetRequiredPropertyParseable<Color>("color", s => Color.Parse(s, CultureInfo.InvariantCulture));
+    var @class = element.GetOptionalProperty<string>("class").GetValueOr("");
+    var color = element.GetRequiredPropertyParseable<Color>("color");
     var name = element.GetRequiredProperty<string>("name");
-    var probability = element.GetOptionalProperty<float>("probability", 1.0f);
-    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties, []);
-    var tile = element.GetOptionalProperty<int>("tile", 0);
+    var probability = element.GetOptionalProperty<float>("probability").GetValueOr(1.0f);
+    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties).GetValueOr([]);
+    var tile = element.GetOptionalProperty<int>("tile").GetValueOr(0);
 
     return new WangColor
     {
@@ -249,7 +249,7 @@ public abstract partial class TmjReaderBase
   internal static WangTile ReadWangTile(JsonElement element)
   {
     var tileID = element.GetRequiredProperty<uint>("tileid");
-    var wangID = element.GetOptionalPropertyCustom<List<byte>>("wangid", e => e.GetValueAsList<byte>(el => (byte)el.GetUInt32()), []);
+    var wangID = element.GetOptionalPropertyCustom<List<byte>>("wangid", e => e.GetValueAsList<byte>(el => (byte)el.GetUInt32())).GetValueOr([]);
 
     return new WangTile
     {
diff --git a/src/DotTiled/Serialization/Tmx/TmxReaderBase.ObjectLayer.cs b/src/DotTiled/Serialization/Tmx/TmxReaderBase.ObjectLayer.cs
index af2e759..67cd69a 100644
--- a/src/DotTiled/Serialization/Tmx/TmxReaderBase.ObjectLayer.cs
+++ b/src/DotTiled/Serialization/Tmx/TmxReaderBase.ObjectLayer.cs
@@ -301,10 +301,10 @@ public abstract partial class TmxReaderBase
     // No attributes
 
     // At most one of
-    Tileset? tileset = null;
+    Tileset tileset = null;
 
     // Should contain exactly one of
-    DotTiled.Object? obj = null;
+    DotTiled.Object obj = null;
 
     _reader.ProcessChildren("template", (r, elementName) => elementName switch
     {
diff --git a/src/DotTiled/Template.cs b/src/DotTiled/Template.cs
index 56052de..24b237e 100644
--- a/src/DotTiled/Template.cs
+++ b/src/DotTiled/Template.cs
@@ -8,7 +8,7 @@ public class Template
   /// <summary>
   /// If the template represents a tile object, this property will contain the tileset that the tile belongs to.
   /// </summary>
-  public Tileset? Tileset { get; set; }
+  public Optional<Tileset> Tileset { get; set; } = Optional<Tileset>.Empty;
 
   /// <summary>
   /// The object that this template represents.