diff --git a/tutorial/netstd/Server/Server.csproj b/tutorial/netstd/Server/Server.csproj
index 9da3249..b63967b 100644
--- a/tutorial/netstd/Server/Server.csproj
+++ b/tutorial/netstd/Server/Server.csproj
@@ -20,6 +20,7 @@
 
   <PropertyGroup>
     <TargetFramework>net5.0</TargetFramework>
+    <LangVersion>9.0</LangVersion>
     <AssemblyName>Server</AssemblyName>
     <PackageId>Server</PackageId>
     <OutputType>Exe</OutputType>