TestCaseAttribute can't convert int to nullable long

[ar7z1]

I've tried to run the test:

[TestCase(0)]
public void Test1(long? x)
{
    ...
}

And it threw the error:

System.ArgumentException : Object of type 'System.Int32' cannot be converted to type 'System.Nullable`1[System.Int64]'.
   at System.RuntimeType.TryChangeType(Object value, Binder binder, CultureInfo culture, Boolean needsSpecialCast)
   at System.Reflection.MethodBase.CheckArguments(Object[] parameters, Binder binder, BindingFlags invokeAttr, CultureInfo culture, Signature sig)
   at System.Reflection.RuntimeMethodInfo.InvokeArgumentsCheck(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at NUnit.Framework.Internal.Reflect.InvokeMethod(MethodInfo method, Object fixture, Object[] args)