C# logging nano-framework

NanoLog.cs

public static class NanoLog
{
    public static void Write(params object[] objs)
    {
        var logDir = System.Environment.GetEnvironmentVariable("SystemDrive") + @"\NanoLog";
        if (!System.IO.Directory.Exists(logDir))
            System.IO.Directory.CreateDirectory(logDir);
        var logName = typeof(NanoLog).Assembly.GetName().Name + ".debug.log";
        var logPath = System.IO.Path.Combine(logDir, logName);
        var timestamp = System.DateTime.Now.ToString("HH:mm:ss.fff");
        var asStrings = System.Array.ConvertAll(objs, System.Convert.ToString);
        var line = $"{timestamp}: {string.Join(" - ", asStrings)}";
        lock (_lock)
            System.IO.File.AppendAllLines(logPath, new[] { line });
    }

    static object _lock = new object();
}