Is there a way to get the MethodInfo of a private method inside a Portable Class Library code?

I have a private method that I need to get its MethodInfo inside a PCL code.

this.GetType().GetTypeInfo().GetDeclaredMethods("ToNullableDouble").First(m=>m.IsStatic && m.IsPrivate)

Above code doesn't work because GetDeclaredMethods returns only public methods.