diff --git a/.gitmodules b/.gitmodules
index 773b291467..8d13c6572c 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -10,4 +10,7 @@
 	url = https://github.com/AvaloniaUI/OmniXAML.git
 [submodule "src/Markup/Avalonia.Markup.Xaml/glass"]
 	path = src/Markup/Avalonia.Markup.Xaml/glass
-	url = https://github.com/SuperJMN/glass
\ No newline at end of file
+	url = https://github.com/SuperJMN/glass
+[submodule "src/Markup/Avalonia.Markup.Xaml/PortableXaml/portable.xaml.github"]
+	path = src/Markup/Avalonia.Markup.Xaml/PortableXaml/portable.xaml.github
+	url = https://github.com/cwensley/Portable.Xaml.git
diff --git a/src/Markup/Avalonia.Markup.Xaml/Avalonia.Markup.Xaml.csproj b/src/Markup/Avalonia.Markup.Xaml/Avalonia.Markup.Xaml.csproj
index 2637cbc068..46dbe1566c 100644
--- a/src/Markup/Avalonia.Markup.Xaml/Avalonia.Markup.Xaml.csproj
+++ b/src/Markup/Avalonia.Markup.Xaml/Avalonia.Markup.Xaml.csproj
@@ -10,7 +10,7 @@
     <DebugType>full</DebugType>
     <Optimize>false</Optimize>
     <OutputPath>bin\Debug\</OutputPath>
-    <DefineConstants>TRACE;DEBUG</DefineConstants>
+    <DefineConstants>TRACE;DEBUG;NETSTANDARD1_3;PCL;NETSTANDARD</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
     <NoWarn>CS1591</NoWarn>
@@ -19,7 +19,7 @@
     <DebugType>pdbonly</DebugType>
     <Optimize>true</Optimize>
     <OutputPath>bin\Release\</OutputPath>
-    <DefineConstants>TRACE</DefineConstants>
+    <DefineConstants>NETSTANDARD1_3;PCL;NETSTANDARD</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
     <DocumentationFile>bin\Release\Avalonia.Markup.Xaml.XML</DocumentationFile>
@@ -293,6 +293,7 @@
     <Compile Include="Templates\TemplateContent.cs" />
     <Compile Include="Templates\TemplateLoader.cs" />
     <Compile Include="Templates\TreeDataTemplate.cs" />
+    <Compile Include="PortableXaml\portable.xaml.github\src\Portable.Xaml\**\*.cs" Exclude="PortableXaml\portable.xaml.github\src\Portable.Xaml\Assembly\**\*.cs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\Avalonia.Animation\Avalonia.Animation.csproj" />
@@ -304,7 +305,9 @@
     <ProjectReference Include="..\..\Avalonia.Visuals\Avalonia.Visuals.csproj" />
     <ProjectReference Include="..\..\Avalonia.Styling\Avalonia.Styling.csproj" />
     <ProjectReference Include="..\Avalonia.Markup\Avalonia.Markup.csproj" />
-    <PackageReference Include="Portable.Xaml" Version="0.16.0" />
+    <PackageReference Include="System.ComponentModel.TypeConverter" Version="4.3.0" />
+    <PackageReference Include="System.Runtime.Serialization.Primitives" Version="4.3.0" />
+    <PackageReference Include="System.Xml.XmlDocument" Version="4.3.0" />
   </ItemGroup>
   <ItemGroup>
     <Content Include="glass\Glass.Core\Glass.Core.csproj" />
diff --git a/src/Markup/Avalonia.Markup.Xaml/PortableXaml/AvaloniaXamlObjectWriter.cs b/src/Markup/Avalonia.Markup.Xaml/PortableXaml/AvaloniaXamlObjectWriter.cs
index 40bff5ed0b..f10de1a32f 100644
--- a/src/Markup/Avalonia.Markup.Xaml/PortableXaml/AvaloniaXamlObjectWriter.cs
+++ b/src/Markup/Avalonia.Markup.Xaml/PortableXaml/AvaloniaXamlObjectWriter.cs
@@ -54,7 +54,7 @@ namespace Avalonia.Markup.Xaml.PortableXaml
             base.Dispose(disposing);
         }
 
-        protected override void OnAfterBeginInit(object value)
+        protected internal override void OnAfterBeginInit(object value)
         {
             //not called for avalonia objects
             //as it's called inly for
@@ -62,7 +62,7 @@ namespace Avalonia.Markup.Xaml.PortableXaml
             base.OnAfterBeginInit(value);
         }
 
-        protected override void OnAfterEndInit(object value)
+        protected internal override void OnAfterEndInit(object value)
         {
             //not called for avalonia objects
             //as it's called inly for
@@ -70,7 +70,7 @@ namespace Avalonia.Markup.Xaml.PortableXaml
             base.OnAfterEndInit(value);
         }
 
-        protected override void OnAfterProperties(object value)
+        protected internal override void OnAfterProperties(object value)
         {
             _delayedValuesHelper.EndInit(value);
 
@@ -82,7 +82,7 @@ namespace Avalonia.Markup.Xaml.PortableXaml
             HandleEndEdit(value);
         }
 
-        protected override void OnBeforeProperties(object value)
+        protected internal override void OnBeforeProperties(object value)
         {
             //OnAfterBeginInit is not called as it supports only
             //Portable.Xaml.ComponentModel.ISupportInitialize
@@ -94,7 +94,7 @@ namespace Avalonia.Markup.Xaml.PortableXaml
             base.OnBeforeProperties(value);
         }
 
-        protected override bool OnSetValue(object target, XamlMember member, object value)
+        protected internal override bool OnSetValue(object target, XamlMember member, object value)
         {
             if (_delayedValuesHelper.TryAdd(target, member, value))
             {
diff --git a/src/Markup/Avalonia.Markup.Xaml/PortableXaml/AvaloniaXamlSchemaContext.cs b/src/Markup/Avalonia.Markup.Xaml/PortableXaml/AvaloniaXamlSchemaContext.cs
index ee20be0efa..bdb21abd77 100644
--- a/src/Markup/Avalonia.Markup.Xaml/PortableXaml/AvaloniaXamlSchemaContext.cs
+++ b/src/Markup/Avalonia.Markup.Xaml/PortableXaml/AvaloniaXamlSchemaContext.cs
@@ -32,7 +32,7 @@ namespace Avalonia.Markup.Xaml.PortableXaml
 
         private IRuntimeTypeProvider _avaloniaTypeProvider;
 
-        protected override XamlType GetXamlType(string xamlNamespace, string name, params XamlType[] typeArguments)
+        protected internal override XamlType GetXamlType(string xamlNamespace, string name, params XamlType[] typeArguments)
         {
             XamlType type = null;
             try
@@ -142,10 +142,10 @@ namespace Avalonia.Markup.Xaml.PortableXaml
 
         #endregion Workaround for bug in Portablexaml system types like double,int etc ...
 
-        protected override ICustomAttributeProvider GetCustomAttributeProvider(Type type)
+        protected internal override ICustomAttributeProvider GetCustomAttributeProvider(Type type)
                                     => new AvaloniaTypeAttributeProvider(type);
 
-        protected override ICustomAttributeProvider GetCustomAttributeProvider(MemberInfo member)
+        protected internal override ICustomAttributeProvider GetCustomAttributeProvider(MemberInfo member)
                                     => new AvaloniaMemberAttributeProvider(member);
 
         public override XamlType GetXamlType(Type type)
@@ -187,7 +187,7 @@ namespace Avalonia.Markup.Xaml.PortableXaml
             return null;
         }
 
-        protected override XamlMember GetAttachableProperty(string attachablePropertyName, MethodInfo getter, MethodInfo setter)
+        protected internal override XamlMember GetAttachableProperty(string attachablePropertyName, MethodInfo getter, MethodInfo setter)
         {
             var key = MemberKey.Create(getter ?? setter, attachablePropertyName, "a");
 
@@ -218,7 +218,7 @@ namespace Avalonia.Markup.Xaml.PortableXaml
             return _cachedMembers[key] = result;
         }
 
-        protected override XamlMember GetProperty(PropertyInfo pi)
+        protected internal override XamlMember GetProperty(PropertyInfo pi)
         {
             Type objType = pi.DeclaringType;
             string name = pi.Name;
diff --git a/src/Markup/Avalonia.Markup.Xaml/PortableXaml/portable.xaml.github b/src/Markup/Avalonia.Markup.Xaml/PortableXaml/portable.xaml.github
new file mode 160000
index 0000000000..d50730ab59
--- /dev/null
+++ b/src/Markup/Avalonia.Markup.Xaml/PortableXaml/portable.xaml.github
@@ -0,0 +1 @@
+Subproject commit d50730ab59aed99cd2f8aeb4975fcc19d23bb54f