diff --git a/X10D.WinForms/X10D.WinForms.csproj b/X10D.WinForms/X10D.WinForms.csproj
index 93359cd..29f196b 100644
--- a/X10D.WinForms/X10D.WinForms.csproj
+++ b/X10D.WinForms/X10D.WinForms.csproj
@@ -21,6 +21,7 @@
     <DefineConstants>DEBUG;TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
+    <LangVersion>8.0</LangVersion>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
     <DebugType>pdbonly</DebugType>
@@ -29,6 +30,7 @@
     <DefineConstants>TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
+    <LangVersion>8.0</LangVersion>
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />
diff --git a/X10D.sln b/X10D.sln
index 3a505a6..9b3182a 100644
--- a/X10D.sln
+++ b/X10D.sln
@@ -9,7 +9,7 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "X10D.Drawing", "X10D.Drawin
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "X10D.Unity", "X10D.Unity\X10D.Unity.csproj", "{2657EF66-0334-4A5A-8C24-6C949224A989}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "X10D", "X10D\X10D.csproj", "{4A8CC062-8B82-4625-B3CC-7DBEAB2AF149}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "X10D", "X10D\X10D.csproj", "{4A8CC062-8B82-4625-B3CC-7DBEAB2AF149}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution