diff --git a/ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/UpDownBase/UpDownBase.cs b/ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/Core/Primitives/UpDownBase.cs
similarity index 95%
rename from ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/UpDownBase/UpDownBase.cs
rename to ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/Core/Primitives/UpDownBase.cs
index fb62b610..5a70b703 100644
--- a/ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/UpDownBase/UpDownBase.cs
+++ b/ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/Core/Primitives/UpDownBase.cs
@@ -3,7 +3,7 @@ using System.Windows.Controls;
 using Microsoft.Windows.Controls.Primitives;
 using System.Windows.Input;
 
-namespace Microsoft.Windows.Controls
+namespace Microsoft.Windows.Controls.Primitives
 {
     public abstract class UpDownBase : InputBase
     {
diff --git a/ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/DateTimeUpDown/DateTimeUpDown.cs b/ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/DateTimeUpDown/DateTimeUpDown.cs
index 5805b3dd..c2b08cef 100644
--- a/ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/DateTimeUpDown/DateTimeUpDown.cs
+++ b/ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/DateTimeUpDown/DateTimeUpDown.cs
@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Globalization;
 using System.Windows;
 using System.Windows.Input;
+using Microsoft.Windows.Controls.Primitives;
 
 namespace Microsoft.Windows.Controls
 {
diff --git a/ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/NumericUpDown/NumericUpDown.cs b/ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/NumericUpDown/NumericUpDown.cs
index 0b63606e..86497db3 100644
--- a/ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/NumericUpDown/NumericUpDown.cs
+++ b/ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/NumericUpDown/NumericUpDown.cs
@@ -2,6 +2,7 @@
 using System.Windows;
 using System.Globalization;
 using System.Windows.Input;
+using Microsoft.Windows.Controls.Primitives;
 
 namespace Microsoft.Windows.Controls
 {
diff --git a/ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/WPFToolkit.Extended.csproj b/ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/WPFToolkit.Extended.csproj
index d17ec715..fbed1ecb 100644
--- a/ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/WPFToolkit.Extended.csproj
+++ b/ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/WPFToolkit.Extended.csproj
@@ -116,7 +116,7 @@
     <Compile Include="RichTextBox\Formatters\RtfFormatter.cs" />
     <Compile Include="RichTextBox\Formatters\XamlFormatter.cs" />
     <Compile Include="RichTextBox\RichTextBox.cs" />
-    <Compile Include="UpDownBase\UpDownBase.cs" />
+    <Compile Include="Core\Primitives\UpDownBase.cs" />
     <Compile Include="VisualStates.cs" />
     <Compile Include="MessageBox\VisualStates.MessageBox.cs" />
     <EmbeddedResource Include="Properties\Resources.resx">
@@ -166,6 +166,9 @@
     <Resource Include="RichTextBoxFormatBar\Images\Bullets16.png" />
     <Resource Include="RichTextBoxFormatBar\Images\Numbering16.png" />
   </ItemGroup>
+  <ItemGroup>
+    <Folder Include="UpDownBase\" />
+  </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.