diff --git a/src/Markup/Avalonia.Markup.Xaml/Avalonia.Markup.Xaml.csproj b/src/Markup/Avalonia.Markup.Xaml/Avalonia.Markup.Xaml.csproj
index 32745e1d0b..9260a0c9a2 100644
--- a/src/Markup/Avalonia.Markup.Xaml/Avalonia.Markup.Xaml.csproj
+++ b/src/Markup/Avalonia.Markup.Xaml/Avalonia.Markup.Xaml.csproj
@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
+    <DefineConstants>PCL;NETSTANDARD;NETSTANDARD2_0;HAS_TYPE_CONVERTER;HAS_CUSTOM_ATTRIBUTE_PROVIDER</DefineConstants>
     <EnableDefaultCompileItems>False</EnableDefaultCompileItems>
     <EnableDefaultItems>false</EnableDefaultItems>
   </PropertyGroup>
@@ -9,7 +10,6 @@
     <DebugType>full</DebugType>
     <Optimize>false</Optimize>
     <OutputPath>bin\Debug\</OutputPath>
-    <DefineConstants>TRACE;DEBUG;NETSTANDARD1_3;PCL;NETSTANDARD</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
     <NoWarn>CS1591</NoWarn>
@@ -18,7 +18,6 @@
     <DebugType>pdbonly</DebugType>
     <Optimize>true</Optimize>
     <OutputPath>bin\Release\</OutputPath>
-    <DefineConstants>NETSTANDARD1_3;PCL;NETSTANDARD</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
     <DocumentationFile>bin\Release\Avalonia.Markup.Xaml.xml</DocumentationFile>
@@ -66,7 +65,6 @@
         <Compile Include="Templates\TreeDataTemplate.cs" />
         <Compile Include="XamlLoadException.cs" />
         <Compile Include="PortableXaml\portable.xaml.github\src\Portable.Xaml\**\*.cs" Exclude="PortableXaml\portable.xaml.github\src\Portable.Xaml\Assembly\**\*.cs" />
-        <Compile Remove="**\UriTypeConverter.cs" />
     </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\Avalonia.Animation\Avalonia.Animation.csproj" />
diff --git a/src/Markup/Avalonia.Markup.Xaml/PortableXaml/portable.xaml.github b/src/Markup/Avalonia.Markup.Xaml/PortableXaml/portable.xaml.github
index cdf46d7892..8abbe09592 160000
--- a/src/Markup/Avalonia.Markup.Xaml/PortableXaml/portable.xaml.github
+++ b/src/Markup/Avalonia.Markup.Xaml/PortableXaml/portable.xaml.github
@@ -1 +1 @@
-Subproject commit cdf46d7892def8a6ba29f12a9339147377f7cf5c
+Subproject commit 8abbe09592668efb573ac4d5548ba2d7e464ba78