diff --git a/test/netstd/Client/Client.csproj b/test/netstd/Client/Client.csproj
index 828ea73..d3504d4 100644
--- a/test/netstd/Client/Client.csproj
+++ b/test/netstd/Client/Client.csproj
@@ -20,6 +20,7 @@
 
   <PropertyGroup>
     <TargetFramework>net5.0</TargetFramework>
+    <LangVersion>9.0</LangVersion>
     <AssemblyName>Client</AssemblyName>
     <PackageId>Client</PackageId>
     <OutputType>Exe</OutputType>
diff --git a/test/netstd/Client/Program.cs b/test/netstd/Client/Program.cs
index 7e502cd..bcc02a2 100644
--- a/test/netstd/Client/Program.cs
+++ b/test/netstd/Client/Program.cs
@@ -18,6 +18,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Runtime.InteropServices;
 using ThriftTest;
 
 namespace Client
@@ -26,8 +27,8 @@
     {
         public static int Main(string[] args)
         {
-            if (OperatingSystem.IsWindows())
-            { 
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
                 try
                 {
                     Console.SetBufferSize(Console.BufferWidth, 4096);
@@ -69,5 +70,3 @@
         }
     }
 }
-
-