diff --git a/Generator.cs b/Generator.cs
index 0fa7403..f5f9e14 100644
--- a/Generator.cs
+++ b/Generator.cs
@@ -293,7 +293,7 @@ namespace WTelegram
 				while ((line = sr.ReadLine()) != null)
 				{
 					if (currentLayer != 0 && line.StartsWith("\t\tpublic const int Layer"))
-						sw.WriteLine($"\t\tpublic const int Layer = {currentLayer};\t\t\t\t// fetched {DateTime.UtcNow}");
+						sw.WriteLine($"\t\tpublic const int Layer = {currentLayer};\t\t\t\t\t// fetched {DateTime.UtcNow}");
 					else
 						sw.WriteLine(line);
 					if (line == myTag)
diff --git a/Helpers.cs b/Helpers.cs
index c38cf66..a39348c 100644
--- a/Helpers.cs
+++ b/Helpers.cs
@@ -47,7 +47,7 @@ namespace WTelegram
 			return result;
 		}
 
-		public static ulong PQFactorize(ulong pq) // ported from https://github.com/tdlib/td/blob/master/tdutils/td/utils/crypto.cpp#L90
+		internal static ulong PQFactorize(ulong pq) // ported from https://github.com/tdlib/td/blob/master/tdutils/td/utils/crypto.cpp#L90
 		{
 			if (pq < 2) return 1;
 			var random = new Random();
diff --git a/TL.Table.cs b/TL.Table.cs
index 60db95a..bacc29b 100644
--- a/TL.Table.cs
+++ b/TL.Table.cs
@@ -7,6 +7,7 @@ namespace TL
 	{
 		public const int Layer = 121;				// fetched 07/08/2021 01:34:33
 		public const int VectorCtor = 0x1CB5C415;
+		public const int NullCtor = 0x56730BCC;
 
 		internal readonly static Dictionary<uint, Type> Table = new()
 		{
diff --git a/TL.cs b/TL.cs
index 342e022..a23b18e 100644
--- a/TL.cs
+++ b/TL.cs
@@ -55,7 +55,10 @@ namespace TL
 			{
 				if (((ifFlag = field.GetCustomAttribute<IfFlagAttribute>()) != null) && (flags & (1 << ifFlag.Bit)) == 0) continue;
 				object value = field.GetValue(obj);
-				SerializeValue(writer, value);
+				if (value == null)
+					SerializeNull(writer, field.FieldType);
+				else
+					SerializeValue(writer, value);
 				if (field.Name.Equals("Flags", StringComparison.OrdinalIgnoreCase)) flags = (int)value;
 			}
 		}
@@ -207,6 +210,15 @@ namespace TL
 			return bytes;
 		}
 
+		internal static void SerializeNull(BinaryWriter writer, Type type)
+		{
+			if (!type.IsArray)
+				writer.Write(NullCtor);
+			else if (type != typeof(byte[]))	// null arrays are serialized as empty
+				writer.Write(VectorCtor);
+			writer.Write(0);
+		}
+
 		private static _Message[] DeserializeMessages(BinaryReader reader)
 		{
 			int count = reader.ReadInt32();