diff --git a/src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/RelativeSourceExtension.cs b/src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/RelativeSourceExtension.cs
index c9ec973f20..ab82b7a28b 100644
--- a/src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/RelativeSourceExtension.cs
+++ b/src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/RelativeSourceExtension.cs
@@ -1,7 +1,7 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
-using Avalonia.Markup.Data;
+using Avalonia.Data;
 
 namespace Avalonia.Markup.Xaml.MarkupExtensions
 {
diff --git a/src/Markup/Avalonia.Markup.Xaml/PortableXaml/AvaloniaRuntimeTypeProvider.cs b/src/Markup/Avalonia.Markup.Xaml/PortableXaml/AvaloniaRuntimeTypeProvider.cs
index 9cb2cc6cd8..3933a6ff19 100644
--- a/src/Markup/Avalonia.Markup.Xaml/PortableXaml/AvaloniaRuntimeTypeProvider.cs
+++ b/src/Markup/Avalonia.Markup.Xaml/PortableXaml/AvaloniaRuntimeTypeProvider.cs
@@ -6,6 +6,7 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
 using Avalonia.Controls;
+using Avalonia.Data;
 using Avalonia.Markup.Data;
 using Avalonia.Markup.Xaml.Templates;
 using Avalonia.Media;
diff --git a/src/Markup/Avalonia.Markup/Avalonia.Markup.csproj b/src/Markup/Avalonia.Markup/Avalonia.Markup.csproj
index 32045f446c..6e10509de6 100644
--- a/src/Markup/Avalonia.Markup/Avalonia.Markup.csproj
+++ b/src/Markup/Avalonia.Markup/Avalonia.Markup.csproj
@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
+    <RootNamespace>Avalonia</RootNamespace>
   </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\Avalonia.Base\Avalonia.Base.csproj" />
diff --git a/src/Markup/Avalonia.Markup/Data/Binding.cs b/src/Markup/Avalonia.Markup/Data/Binding.cs
index 31131ecfa0..96fc2986e8 100644
--- a/src/Markup/Avalonia.Markup/Data/Binding.cs
+++ b/src/Markup/Avalonia.Markup/Data/Binding.cs
@@ -7,13 +7,12 @@ using System.Reactive;
 using System.Reactive.Linq;
 using System.Reflection;
 using Avalonia.Controls;
-using Avalonia.Data;
 using Avalonia.Data.Converters;
 using Avalonia.Data.Core;
 using Avalonia.LogicalTree;
 using Avalonia.VisualTree;
 
-namespace Avalonia.Markup.Data
+namespace Avalonia.Data
 {
     /// <summary>
     /// A XAML binding.
diff --git a/src/Markup/Avalonia.Markup/Data/MultiBinding.cs b/src/Markup/Avalonia.Markup/Data/MultiBinding.cs
index 4c7d9396ac..f6f62dcd1d 100644
--- a/src/Markup/Avalonia.Markup/Data/MultiBinding.cs
+++ b/src/Markup/Avalonia.Markup/Data/MultiBinding.cs
@@ -8,11 +8,10 @@ using System.Linq;
 using System.Reactive.Linq;
 using System.Reactive.Subjects;
 using Avalonia.Controls;
-using Avalonia.Data;
 using Avalonia.Data.Converters;
 using Avalonia.Metadata;
 
-namespace Avalonia.Markup.Data
+namespace Avalonia.Data
 {
     /// <summary>
     /// A XAML binding that calculates an aggregate value from multiple child <see cref="Bindings"/>.
diff --git a/src/Markup/Avalonia.Markup/Data/RelativeSource.cs b/src/Markup/Avalonia.Markup/Data/RelativeSource.cs
index 9a3b770212..42b43622da 100644
--- a/src/Markup/Avalonia.Markup/Data/RelativeSource.cs
+++ b/src/Markup/Avalonia.Markup/Data/RelativeSource.cs
@@ -3,7 +3,7 @@
 
 using System;
 
-namespace Avalonia.Markup.Data
+namespace Avalonia.Data
 {
     /// <summary>
     /// Defines the mode of a <see cref="RelativeSource"/> object.
diff --git a/src/Markup/Avalonia.Markup/Data/DelayedBinding.cs b/src/Markup/Avalonia.Markup/Markup/Data/DelayedBinding.cs
similarity index 100%
rename from src/Markup/Avalonia.Markup/Data/DelayedBinding.cs
rename to src/Markup/Avalonia.Markup/Markup/Data/DelayedBinding.cs
diff --git a/src/Markup/Avalonia.Markup/Parsers/SelectorGrammar.cs b/src/Markup/Avalonia.Markup/Markup/Parsers/SelectorGrammar.cs
similarity index 100%
rename from src/Markup/Avalonia.Markup/Parsers/SelectorGrammar.cs
rename to src/Markup/Avalonia.Markup/Markup/Parsers/SelectorGrammar.cs
diff --git a/src/Markup/Avalonia.Markup/Parsers/SelectorParser.cs b/src/Markup/Avalonia.Markup/Markup/Parsers/SelectorParser.cs
similarity index 100%
rename from src/Markup/Avalonia.Markup/Parsers/SelectorParser.cs
rename to src/Markup/Avalonia.Markup/Markup/Parsers/SelectorParser.cs
diff --git a/src/Markup/Avalonia.Markup/Properties/AssemblyInfo.cs b/src/Markup/Avalonia.Markup/Properties/AssemblyInfo.cs
index 28f0fd48bd..4651dbab8d 100644
--- a/src/Markup/Avalonia.Markup/Properties/AssemblyInfo.cs
+++ b/src/Markup/Avalonia.Markup/Properties/AssemblyInfo.cs
@@ -5,5 +5,6 @@ using System.Reflection;
 using Avalonia.Metadata;
 using System.Runtime.CompilerServices;
 
+[assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia.Data")]
 [assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia.Markup.Data")]
 [assembly: InternalsVisibleTo("Avalonia.Markup.UnitTests")]
diff --git a/tests/Avalonia.Markup.UnitTests/Data/BindingTests_ElementName.cs b/tests/Avalonia.Markup.UnitTests/Data/BindingTests_ElementName.cs
index a05b121a42..61df0bffdf 100644
--- a/tests/Avalonia.Markup.UnitTests/Data/BindingTests_ElementName.cs
+++ b/tests/Avalonia.Markup.UnitTests/Data/BindingTests_ElementName.cs
@@ -2,6 +2,7 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 using Avalonia.Controls;
+using Avalonia.Data;
 using Avalonia.Markup.Data;
 using Avalonia.UnitTests;
 using Xunit;
diff --git a/tests/Avalonia.Markup.UnitTests/Data/BindingTests_RelativeSource.cs b/tests/Avalonia.Markup.UnitTests/Data/BindingTests_RelativeSource.cs
index 36e801d22d..f2ddec6f3c 100644
--- a/tests/Avalonia.Markup.UnitTests/Data/BindingTests_RelativeSource.cs
+++ b/tests/Avalonia.Markup.UnitTests/Data/BindingTests_RelativeSource.cs
@@ -2,6 +2,7 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 using Avalonia.Controls;
+using Avalonia.Data;
 using Avalonia.Markup.Data;
 using Avalonia.UnitTests;
 using Xunit;
diff --git a/tests/Avalonia.Markup.UnitTests/Data/MultiBindingTests.cs b/tests/Avalonia.Markup.UnitTests/Data/MultiBindingTests.cs
index b341af2810..fb23a38cce 100644
--- a/tests/Avalonia.Markup.UnitTests/Data/MultiBindingTests.cs
+++ b/tests/Avalonia.Markup.UnitTests/Data/MultiBindingTests.cs
@@ -11,7 +11,7 @@ using Avalonia.Controls;
 using Xunit;
 using System.Threading.Tasks;
 using Avalonia.Data.Converters;
-using Avalonia.Markup.Data;
+using Avalonia.Data;
 
 namespace Avalonia.Markup.UnitTests.Data
 {
diff --git a/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/BasicTests.cs b/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/BasicTests.cs
index 43df95cfce..c41cf4a590 100644
--- a/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/BasicTests.cs
+++ b/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/BasicTests.cs
@@ -4,6 +4,7 @@
 using Avalonia.Collections;
 using Avalonia.Controls;
 using Avalonia.Controls.Presenters;
+using Avalonia.Data;
 using Avalonia.Data.Converters;
 using Avalonia.Markup.Data;
 using Avalonia.Markup.Xaml.Styling;
diff --git a/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/TreeDataTemplateTests.cs b/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/TreeDataTemplateTests.cs
index cbcfa16771..4134f5be23 100644
--- a/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/TreeDataTemplateTests.cs
+++ b/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/TreeDataTemplateTests.cs
@@ -3,6 +3,7 @@
 
 using System.Linq;
 using Avalonia.Controls.Templates;
+using Avalonia.Data;
 using Avalonia.Markup.Data;
 using Avalonia.Markup.Xaml.Templates;
 using Avalonia.UnitTests;