diff --git a/Mono.TextTemplating.Build.Tests/Mono.TextTemplating.Build.Tests.csproj b/Mono.TextTemplating.Build.Tests/Mono.TextTemplating.Build.Tests.csproj
index e3dd14d..9f81497 100644
--- a/Mono.TextTemplating.Build.Tests/Mono.TextTemplating.Build.Tests.csproj
+++ b/Mono.TextTemplating.Build.Tests/Mono.TextTemplating.Build.Tests.csproj
@@ -20,7 +20,7 @@
     Microsoft.NET.Test.Sdk brings in a version of NuGet.Frameworks that's older than the one used by MSBuild
     and loads first, thereby breaking loading of MSBuild assemblies. Force-upgrade it.
     -->
-    <PackageReference Include="NuGet.Frameworks" Version="6.7.0" />
+    <PackageReference Include="NuGet.Frameworks" Version="6.9.1" />
     <PackageReference Include="System.Text.Json" Version="7.0.3" />
   </ItemGroup>
 
diff --git a/Mono.TextTemplating/Mono.TextTemplating.CodeCompilation/CSharpLangVersionHelper.cs b/Mono.TextTemplating/Mono.TextTemplating.CodeCompilation/CSharpLangVersionHelper.cs
index 347233c..4235e06 100644
--- a/Mono.TextTemplating/Mono.TextTemplating.CodeCompilation/CSharpLangVersionHelper.cs
+++ b/Mono.TextTemplating/Mono.TextTemplating.CodeCompilation/CSharpLangVersionHelper.cs
@@ -48,7 +48,9 @@ public static bool IsLangVersionArg (string arg) =>
 	//https://docs.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-version-history
 	public static CSharpLangVersion FromNetCoreSdkVersion (SemVersion sdkVersion)
 		=> sdkVersion switch {
-			{ Major: 9 } => CSharpLangVersion.v13_0,
+			// disable .NET 9.0 -> C# 13 mapping for now, as csc in early .NET 9.0 previews
+			// doesn't recognize C# 13 as a valid version option
+			// { Major: 9 } => CSharpLangVersion.v13_0,
 			{ Major: 8 } => CSharpLangVersion.v12_0,
 			{ Major: 7 } => CSharpLangVersion.v11_0,
 			{ Major: 6 } => CSharpLangVersion.v10_0,