diff --git a/src/OpenTK.GLWidget/OpenTK.GLWidget.csproj b/src/OpenTK.GLWidget/OpenTK.GLWidget.csproj
index 6e771eba..aeda128c 100644
--- a/src/OpenTK.GLWidget/OpenTK.GLWidget.csproj
+++ b/src/OpenTK.GLWidget/OpenTK.GLWidget.csproj
@@ -42,7 +42,7 @@
     <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
     <TargetFrameworkProfile />
     <Deterministic>true</Deterministic>
-    <LangVersion>6</LangVersion>
+    <LangVersion>7</LangVersion>
     <RunCodeAnalysis>true</RunCodeAnalysis>
     <CodeAnalysisRuleSet>..\..\stylecop.ruleset</CodeAnalysisRuleSet>
   </PropertyGroup>
@@ -120,8 +120,7 @@
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <Choose>
-    <When
-      Condition="($(DefineConstants.Contains('GTK3')) And ($(TargetFrameworkVersion) == 'v4.0' Or $(TargetFrameworkVersion) == 'v4.0.3' Or $(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6' Or $(TargetFrameworkVersion) == 'v4.6.1' Or $(TargetFrameworkVersion) == 'v4.6.2' Or $(TargetFrameworkVersion) == 'v4.6.3' Or $(TargetFrameworkVersion) == 'v4.7'))">
+    <When Condition="($(DefineConstants.Contains('GTK3')) And ($(TargetFrameworkVersion) == 'v4.0' Or $(TargetFrameworkVersion) == 'v4.0.3' Or $(TargetFrameworkVersion) == 'v4.5' Or $(TargetFrameworkVersion) == 'v4.5.1' Or $(TargetFrameworkVersion) == 'v4.5.2' Or $(TargetFrameworkVersion) == 'v4.5.3' Or $(TargetFrameworkVersion) == 'v4.6' Or $(TargetFrameworkVersion) == 'v4.6.1' Or $(TargetFrameworkVersion) == 'v4.6.2' Or $(TargetFrameworkVersion) == 'v4.6.3' Or $(TargetFrameworkVersion) == 'v4.7'))">
       <ItemGroup>
         <Reference Include="cairo-sharp">
           <HintPath>..\..\packages\gtk-sharp3\lib\net40\cairo-sharp.dll</HintPath>