diff --git a/src/DotTiled/Serialization/Tmj/TmjReaderBase.Group.cs b/src/DotTiled/Serialization/Tmj/TmjReaderBase.Group.cs
index 9548f1c..0df3c10 100644
--- a/src/DotTiled/Serialization/Tmj/TmjReaderBase.Group.cs
+++ b/src/DotTiled/Serialization/Tmj/TmjReaderBase.Group.cs
@@ -17,7 +17,7 @@ public abstract partial class TmjReaderBase
     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 properties = ResolveAndMergeProperties(@class, 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 7034663..3d59779 100644
--- a/src/DotTiled/Serialization/Tmj/TmjReaderBase.ImageLayer.cs
+++ b/src/DotTiled/Serialization/Tmj/TmjReaderBase.ImageLayer.cs
@@ -16,7 +16,7 @@ public abstract partial class TmjReaderBase
     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 properties = ResolveAndMergeProperties(@class, element.GetOptionalPropertyCustom("properties", ReadProperties).GetValueOr([]));
 
     var image = element.GetRequiredProperty<string>("image");
     var repeatX = element.GetOptionalProperty<bool>("repeatx").GetValueOr(false);
diff --git a/src/DotTiled/Serialization/Tmj/TmjReaderBase.ObjectLayer.cs b/src/DotTiled/Serialization/Tmj/TmjReaderBase.ObjectLayer.cs
index 0456157..f90d986 100644
--- a/src/DotTiled/Serialization/Tmj/TmjReaderBase.ObjectLayer.cs
+++ b/src/DotTiled/Serialization/Tmj/TmjReaderBase.ObjectLayer.cs
@@ -19,7 +19,7 @@ public abstract partial class TmjReaderBase
     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 properties = ResolveAndMergeProperties(@class, element.GetOptionalPropertyCustom("properties", ReadProperties).GetValueOr([]));
 
     var x = element.GetOptionalProperty<uint>("x").GetValueOr(0);
     var y = element.GetOptionalProperty<uint>("y").GetValueOr(0);
diff --git a/src/DotTiled/Serialization/Tmj/TmjReaderBase.TileLayer.cs b/src/DotTiled/Serialization/Tmj/TmjReaderBase.TileLayer.cs
index 7c8791a..f33840d 100644
--- a/src/DotTiled/Serialization/Tmj/TmjReaderBase.TileLayer.cs
+++ b/src/DotTiled/Serialization/Tmj/TmjReaderBase.TileLayer.cs
@@ -30,7 +30,7 @@ public abstract partial class TmjReaderBase
     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 properties = ResolveAndMergeProperties(@class, 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);
diff --git a/src/DotTiled/Serialization/Tmj/TmjReaderBase.Tileset.cs b/src/DotTiled/Serialization/Tmj/TmjReaderBase.Tileset.cs
index ea91acf..9263fa9 100644
--- a/src/DotTiled/Serialization/Tmj/TmjReaderBase.Tileset.cs
+++ b/src/DotTiled/Serialization/Tmj/TmjReaderBase.Tileset.cs
@@ -40,7 +40,7 @@ public abstract partial class TmjReaderBase
       "bottomright" => ObjectAlignment.BottomRight,
       _ => throw new JsonException($"Unknown object alignment '{s}'")
     }).GetValueOr(ObjectAlignment.Unspecified);
-    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties).GetValueOr([]);
+    var properties = ResolveAndMergeProperties(@class, element.GetOptionalPropertyCustom("properties", ReadProperties).GetValueOr([]));
     var source = element.GetOptionalProperty<string>("source");
     var spacing = element.GetOptionalProperty<uint>("spacing");
     var tileCount = element.GetOptionalProperty<uint>("tilecount");
@@ -166,8 +166,8 @@ public abstract partial class TmjReaderBase
       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 properties = ResolveAndMergeProperties(type, e.GetOptionalPropertyCustom("properties", ReadProperties).GetValueOr([]));
 
       Optional<Image> imageModel = image.HasValue ? new Image
       {
@@ -207,17 +207,17 @@ public abstract partial class TmjReaderBase
 
   internal Wangset ReadWangset(JsonElement element)
   {
-    var @clalss = element.GetOptionalProperty<string>("class").GetValueOr("");
+    var @class = 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).GetValueOr([]);
+    var properties = ResolveAndMergeProperties(@class, 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
     {
-      Class = @clalss,
+      Class = @class,
       WangColors = colors,
       Name = name,
       Properties = properties,
@@ -232,7 +232,7 @@ public abstract partial class TmjReaderBase
     var color = element.GetRequiredPropertyParseable<Color>("color");
     var name = element.GetRequiredProperty<string>("name");
     var probability = element.GetOptionalProperty<float>("probability").GetValueOr(1.0f);
-    var properties = element.GetOptionalPropertyCustom("properties", ReadProperties).GetValueOr([]);
+    var properties = ResolveAndMergeProperties(@class, element.GetOptionalPropertyCustom("properties", ReadProperties).GetValueOr([]));
     var tile = element.GetOptionalProperty<int>("tile").GetValueOr(0);
 
     return new WangColor
diff --git a/src/DotTiled/Serialization/Tmx/TmxReaderBase.ObjectLayer.cs b/src/DotTiled/Serialization/Tmx/TmxReaderBase.ObjectLayer.cs
index 67cd69a..85c669c 100644
--- a/src/DotTiled/Serialization/Tmx/TmxReaderBase.ObjectLayer.cs
+++ b/src/DotTiled/Serialization/Tmx/TmxReaderBase.ObjectLayer.cs
@@ -34,12 +34,13 @@ public abstract partial class TmxReaderBase
     }).GetValueOr(DrawOrder.TopDown);
 
     // Elements
-    List<IProperty> properties = null;
+    var propertiesCounter = 0;
+    List<IProperty> properties = Helpers.ResolveClassProperties(@class, _customTypeResolver);
     List<DotTiled.Object> objects = [];
 
     _reader.ProcessChildren("objectgroup", (r, elementName) => elementName switch
     {
-      "properties" => () => Helpers.SetAtMostOnce(ref properties, ReadProperties(), "Properties"),
+      "properties" => () => Helpers.SetAtMostOnceUsingCounter(ref properties, Helpers.MergeProperties(properties, ReadProperties()).ToList(), "Properties", ref propertiesCounter),
       "object" => () => objects.Add(ReadObject()),
       _ => r.Skip
     });
@@ -101,7 +102,7 @@ public abstract partial class TmxReaderBase
     // Elements
     DotTiled.Object foundObject = null;
     int propertiesCounter = 0;
-    List<IProperty> properties = propertiesDefault;
+    List<IProperty> properties = Helpers.ResolveClassProperties(type, _customTypeResolver) ?? propertiesDefault;
 
     _reader.ProcessChildren("object", (r, elementName) => elementName switch
     {
diff --git a/src/DotTiled/Serialization/Tmx/TmxReaderBase.TileLayer.cs b/src/DotTiled/Serialization/Tmx/TmxReaderBase.TileLayer.cs
index d3a7106..974215b 100644
--- a/src/DotTiled/Serialization/Tmx/TmxReaderBase.TileLayer.cs
+++ b/src/DotTiled/Serialization/Tmx/TmxReaderBase.TileLayer.cs
@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.Linq;
 
 namespace DotTiled.Serialization.Tmx;
 
@@ -21,13 +22,14 @@ public abstract partial class TmxReaderBase
     var parallaxX = _reader.GetOptionalAttributeParseable<float>("parallaxx").GetValueOr(1.0f);
     var parallaxY = _reader.GetOptionalAttributeParseable<float>("parallaxy").GetValueOr(1.0f);
 
-    List<IProperty> properties = null;
+    var propertiesCounter = 0;
+    List<IProperty> properties = Helpers.ResolveClassProperties(@class, _customTypeResolver);
     Data data = null;
 
     _reader.ProcessChildren("layer", (r, elementName) => elementName switch
     {
       "data" => () => Helpers.SetAtMostOnce(ref data, ReadData(dataUsesChunks), "Data"),
-      "properties" => () => Helpers.SetAtMostOnce(ref properties, ReadProperties(), "Properties"),
+      "properties" => () => Helpers.SetAtMostOnceUsingCounter(ref properties, Helpers.MergeProperties(properties, ReadProperties()).ToList(), "Properties", ref propertiesCounter),
       _ => r.Skip
     });
 
@@ -69,13 +71,14 @@ public abstract partial class TmxReaderBase
     var repeatX = _reader.GetOptionalAttributeParseable<uint>("repeatx").GetValueOr(0) == 1;
     var repeatY = _reader.GetOptionalAttributeParseable<uint>("repeaty").GetValueOr(0) == 1;
 
-    List<IProperty> properties = null;
+    var propertiesCounter = 0;
+    List<IProperty> properties = Helpers.ResolveClassProperties(@class, _customTypeResolver);
     Image image = null;
 
     _reader.ProcessChildren("imagelayer", (r, elementName) => elementName switch
     {
       "image" => () => Helpers.SetAtMostOnce(ref image, ReadImage(), "Image"),
-      "properties" => () => Helpers.SetAtMostOnce(ref properties, ReadProperties(), "Properties"),
+      "properties" => () => Helpers.SetAtMostOnceUsingCounter(ref properties, Helpers.MergeProperties(properties, ReadProperties()).ToList(), "Properties", ref propertiesCounter),
       _ => r.Skip
     });
 
@@ -113,12 +116,13 @@ public abstract partial class TmxReaderBase
     var parallaxX = _reader.GetOptionalAttributeParseable<float>("parallaxx").GetValueOr(1f);
     var parallaxY = _reader.GetOptionalAttributeParseable<float>("parallaxy").GetValueOr(1f);
 
-    List<IProperty> properties = null;
+    var propertiesCounter = 0;
+    List<IProperty> properties = Helpers.ResolveClassProperties(@class, _customTypeResolver);
     List<BaseLayer> layers = [];
 
     _reader.ProcessChildren("group", (r, elementName) => elementName switch
     {
-      "properties" => () => Helpers.SetAtMostOnce(ref properties, ReadProperties(), "Properties"),
+      "properties" => () => Helpers.SetAtMostOnceUsingCounter(ref properties, Helpers.MergeProperties(properties, ReadProperties()).ToList(), "Properties", ref propertiesCounter),
       "layer" => () => layers.Add(ReadTileLayer(false)),
       "objectgroup" => () => layers.Add(ReadObjectLayer()),
       "imagelayer" => () => layers.Add(ReadImageLayer()),
diff --git a/src/DotTiled/Serialization/Tmx/TmxReaderBase.Tileset.cs b/src/DotTiled/Serialization/Tmx/TmxReaderBase.Tileset.cs
index 971e6fd..2fc2540 100644
--- a/src/DotTiled/Serialization/Tmx/TmxReaderBase.Tileset.cs
+++ b/src/DotTiled/Serialization/Tmx/TmxReaderBase.Tileset.cs
@@ -68,7 +68,8 @@ public abstract partial class TmxReaderBase
     Image image = null;
     TileOffset tileOffset = null;
     Grid grid = null;
-    List<IProperty> properties = null;
+    var propertiesCounter = 0;
+    List<IProperty> properties = Helpers.ResolveClassProperties(@class, _customTypeResolver);
     List<Wangset> wangsets = null;
     Transformations transformations = null;
     List<Tile> tiles = [];
@@ -78,7 +79,7 @@ public abstract partial class TmxReaderBase
       "image" => () => Helpers.SetAtMostOnce(ref image, ReadImage(), "Image"),
       "tileoffset" => () => Helpers.SetAtMostOnce(ref tileOffset, ReadTileOffset(), "TileOffset"),
       "grid" => () => Helpers.SetAtMostOnce(ref grid, ReadGrid(), "Grid"),
-      "properties" => () => Helpers.SetAtMostOnce(ref properties, ReadProperties(), "Properties"),
+      "properties" => () => Helpers.SetAtMostOnceUsingCounter(ref properties, Helpers.MergeProperties(properties, ReadProperties()).ToList(), "Properties", ref propertiesCounter),
       "wangsets" => () => Helpers.SetAtMostOnce(ref wangsets, ReadWangsets(), "Wangsets"),
       "transformations" => () => Helpers.SetAtMostOnce(ref transformations, ReadTransformations(), "Transformations"),
       "tile" => () => tiles.Add(ReadTile()),
@@ -197,14 +198,15 @@ public abstract partial class TmxReaderBase
     var height = _reader.GetOptionalAttributeParseable<uint>("height");
 
     // Elements
-    List<IProperty> properties = null;
+    var propertiesCounter = 0;
+    List<IProperty> properties = Helpers.ResolveClassProperties(type, _customTypeResolver);
     Image image = null;
     ObjectLayer objectLayer = null;
     List<Frame> animation = null;
 
     _reader.ProcessChildren("tile", (r, elementName) => elementName switch
     {
-      "properties" => () => Helpers.SetAtMostOnce(ref properties, ReadProperties(), "Properties"),
+      "properties" => () => Helpers.SetAtMostOnceUsingCounter(ref properties, Helpers.MergeProperties(properties, ReadProperties()).ToList(), "Properties", ref propertiesCounter),
       "image" => () => Helpers.SetAtMostOnce(ref image, ReadImage(), "Image"),
       "objectgroup" => () => Helpers.SetAtMostOnce(ref objectLayer, ReadObjectLayer(), "ObjectLayer"),
       "animation" => () => Helpers.SetAtMostOnce(ref animation, r.ReadList<Frame>("animation", "frame", (ar) =>
@@ -243,13 +245,14 @@ public abstract partial class TmxReaderBase
     var tile = _reader.GetRequiredAttributeParseable<int>("tile");
 
     // Elements
-    List<IProperty> properties = null;
+    var propertiesCounter = 0;
+    List<IProperty> properties = Helpers.ResolveClassProperties(@class, _customTypeResolver);
     List<WangColor> wangColors = [];
     List<WangTile> wangTiles = [];
 
     _reader.ProcessChildren("wangset", (r, elementName) => elementName switch
     {
-      "properties" => () => Helpers.SetAtMostOnce(ref properties, ReadProperties(), "Properties"),
+      "properties" => () => Helpers.SetAtMostOnceUsingCounter(ref properties, Helpers.MergeProperties(properties, ReadProperties()).ToList(), "Properties", ref propertiesCounter),
       "wangcolor" => () => wangColors.Add(ReadWangColor()),
       "wangtile" => () => wangTiles.Add(ReadWangTile()),
       _ => r.Skip
@@ -279,11 +282,12 @@ public abstract partial class TmxReaderBase
     var probability = _reader.GetOptionalAttributeParseable<float>("probability").GetValueOr(0f);
 
     // Elements
-    List<IProperty> properties = null;
+    var propertiesCounter = 0;
+    List<IProperty> properties = Helpers.ResolveClassProperties(@class, _customTypeResolver);
 
     _reader.ProcessChildren("wangcolor", (r, elementName) => elementName switch
     {
-      "properties" => () => Helpers.SetAtMostOnce(ref properties, ReadProperties(), "Properties"),
+      "properties" => () => Helpers.SetAtMostOnceUsingCounter(ref properties, Helpers.MergeProperties(properties, ReadProperties()).ToList(), "Properties", ref propertiesCounter),
       _ => r.Skip
     });