diff --git a/CSharp/Libraries/UniversalEditor.UserInterface/UniversalEditor.UserInterface.csproj b/CSharp/Libraries/UniversalEditor.UserInterface/UniversalEditor.UserInterface.csproj
index e46293f3..6dee2db0 100644
--- a/CSharp/Libraries/UniversalEditor.UserInterface/UniversalEditor.UserInterface.csproj
+++ b/CSharp/Libraries/UniversalEditor.UserInterface/UniversalEditor.UserInterface.csproj
@@ -56,6 +56,7 @@
     <Compile Include="Common\Reflection.cs" />
     <Compile Include="Engine.cs" />
     <Compile Include="HostApplication.cs" />
+    <Compile Include="HostApplicationMessage.cs" />
     <Compile Include="HostApplicationOutputWindow.cs" />
     <Compile Include="IEditorImplementation.cs" />
     <Compile Include="IHostApplicationWindow.cs" />
diff --git a/CSharp/Plugins/UniversalEditor.Plugins.FileSystem/UniversalEditor.Plugins.FileSystem.csproj b/CSharp/Plugins/UniversalEditor.Plugins.FileSystem/UniversalEditor.Plugins.FileSystem.csproj
index 255ad440..c725c156 100644
--- a/CSharp/Plugins/UniversalEditor.Plugins.FileSystem/UniversalEditor.Plugins.FileSystem.csproj
+++ b/CSharp/Plugins/UniversalEditor.Plugins.FileSystem/UniversalEditor.Plugins.FileSystem.csproj
@@ -155,6 +155,10 @@
       <Project>{a92d520b-ffa3-4464-8cf6-474d18959e03}</Project>
       <Name>UniversalEditor.Core</Name>
     </ProjectReference>
+    <ProjectReference Include="..\..\Libraries\UniversalEditor.UserInterface\UniversalEditor.UserInterface.csproj">
+      <Project>{8622ebc4-8e20-476e-b284-33d472081f5c}</Project>
+      <Name>UniversalEditor.UserInterface</Name>
+    </ProjectReference>
     <ProjectReference Include="..\UniversalEditor.Essential\UniversalEditor.Essential.csproj">
       <Project>{30467e5c-05bc-4856-aadc-13906ef4cadd}</Project>
       <Name>UniversalEditor.Essential</Name>