test all frameworks on windows
diff --git a/csharp/buildall.bat b/csharp/buildall.bat
index 89cf8f0..821ffb3 100644
--- a/csharp/buildall.bat
+++ b/csharp/buildall.bat
@@ -4,7 +4,7 @@
 
 echo Running tests.
 
-dotnet test -f netcoreapp2.1 src/Google.Protobuf.Test/Google.Protobuf.Test.csproj || goto :error
+dotnet test src/Google.Protobuf.Test/Google.Protobuf.Test.csproj || goto :error
 
 goto :EOF