diff --git a/pytiled_parser/objects.py b/pytiled_parser/objects.py
index 3c9a8f1..1aa6731 100644
--- a/pytiled_parser/objects.py
+++ b/pytiled_parser/objects.py
@@ -233,7 +233,7 @@ class TileLayer(Layer):
     """
 
     size: Size
-    data: LayerData
+    layer_data: LayerData
 
 
 @attr.s(auto_attribs=True, kw_only=True)
@@ -261,9 +261,9 @@ class TiledObject:
     gid: Optional[int] = None
 
     location: OrderedPair
-    size: Size = Size(0, 0)
-    rotation: int = 0
-    opacity: float = 1
+    size: Optional[Size] = None
+    rotation: int
+    opacity: Optional[float] = None
 
     name: Optional[str] = None
     type: Optional[str] = None
diff --git a/pytiled_parser/xml_parser.py b/pytiled_parser/xml_parser.py
index 7eca97c..d350011 100644
--- a/pytiled_parser/xml_parser.py
+++ b/pytiled_parser/xml_parser.py
@@ -234,7 +234,7 @@ def _parse_tile_layer(element: etree.Element,) -> objects.TileLayer:
 
     data_element = element.find("./data")
     assert data_element is not None
-    data: objects.LayerData = _parse_data(data_element, width)
+    layer_data: objects.LayerData = _parse_data(data_element, width)
 
     return objects.TileLayer(
         id_=id_,
@@ -243,7 +243,7 @@ def _parse_tile_layer(element: etree.Element,) -> objects.TileLayer:
         opacity=opacity,
         properties=properties,
         size=size,
-        data=data,
+        layer_data=layer_data,
     )