how to modify static feild type[] to new type[]

[billpeace]

class Program
{
public static byte[] byte_1 = new byte[] { 2, 3, 4 };
}

var a = AssemblyDefinition.ReadAssembly(filePath);
var t = a.MainModule.Types.Single(ct => ct.Name == "Program");
if (t != null)
{
var f = t.Fields.First(p => p.Name == "byte_1");
f.InitialValue = new byte[] { 2, 3, 4, 5 }; // no change
if (f != null)
{

            }
}

How to modify? Thanks very much