Monogame nuget 3.2 package built using .NET 4.5?

I’m using the monogame nuget binaries package from and building for .Net 4 however I get build problems like ;

Error 1 The type ‘System.IDisposable’ is defined in an assembly that is not referenced. You must add a reference to assembly ‘System.Runtime, Version=, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a’.

According to ILSpy then the monogame dll contains the reference System.Runtime, Version=, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
which I believe is a façade for .NET 4.5. I don’t have 4.5 only 4 so cannot add the required reference and so although I want to target version 4 it seems the nuget build contains the wrong reference.

Well looks like the DirectX version is targeted for .NET 4.5 whereas WIndowsGL is .NET 4. So I suppose DirectX is supposed to target Windows 8? Something of a pain for non-Windows 8 DirectX users then! So I can cure it by building the framework myself and copying the files across however would prefer to keep it via nuget and so if anyone has a solution for NuGet local stream would be appreciated.