diff --git a/DiscordChatExporter.Core.Models/Attachment.cs b/DiscordChatExporter.Core.Models/Attachment.cs
index 8a7d10e..5510445 100644
--- a/DiscordChatExporter.Core.Models/Attachment.cs
+++ b/DiscordChatExporter.Core.Models/Attachment.cs
@@ -6,7 +6,7 @@ namespace DiscordChatExporter.Core.Models
 {
     // https://discordapp.com/developers/docs/resources/channel#attachment-object
 
-    public partial class Attachment
+    public partial class Attachment : IHasId
     {
         public string Id { get; }
 
diff --git a/DiscordChatExporter.Core.Models/Channel.cs b/DiscordChatExporter.Core.Models/Channel.cs
index 34b8d91..1035030 100644
--- a/DiscordChatExporter.Core.Models/Channel.cs
+++ b/DiscordChatExporter.Core.Models/Channel.cs
@@ -2,13 +2,13 @@
 {
     // https://discordapp.com/developers/docs/resources/channel#channel-object
 
-    public partial class Channel
+    public partial class Channel : IHasId
     {
         public string Id { get; }
 
         public string? ParentId { get; }
 
-        public string? GuildId { get; }
+        public string GuildId { get; }
 
         public string Name { get; }
 
@@ -16,7 +16,7 @@
 
         public ChannelType Type { get; }
 
-        public Channel(string id, string? parentId, string? guildId, string name, string? topic, ChannelType type)
+        public Channel(string id, string? parentId, string guildId, string name, string? topic, ChannelType type)
         {
             Id = id;
             ParentId = parentId;
@@ -32,6 +32,6 @@
     public partial class Channel
     {
         public static Channel CreateDeletedChannel(string id) =>
-            new Channel(id, null, null, "deleted-channel", null, ChannelType.GuildTextChat);
+            new Channel(id, null, "unknown-guild", "deleted-channel", null, ChannelType.GuildTextChat);
     }
 }
\ No newline at end of file
diff --git a/DiscordChatExporter.Core.Models/Emoji.cs b/DiscordChatExporter.Core.Models/Emoji.cs
index 19af4e4..1b21bd1 100644
--- a/DiscordChatExporter.Core.Models/Emoji.cs
+++ b/DiscordChatExporter.Core.Models/Emoji.cs
@@ -6,7 +6,7 @@ namespace DiscordChatExporter.Core.Models
 {
     // https://discordapp.com/developers/docs/resources/emoji#emoji-object
 
-    public partial class Emoji
+    public partial class Emoji : IHasId
     {
         public string? Id { get; }
 
diff --git a/DiscordChatExporter.Core.Models/FileSize.cs b/DiscordChatExporter.Core.Models/FileSize.cs
index d52464b..23ef46f 100644
--- a/DiscordChatExporter.Core.Models/FileSize.cs
+++ b/DiscordChatExporter.Core.Models/FileSize.cs
@@ -30,7 +30,6 @@ namespace DiscordChatExporter.Core.Models
         {
             get
             {
-                // Absolute value is used to deal with negative values
                 if (Math.Abs(PetaBytes) >= 1)
                     return PetaByteSymbol;
 
@@ -54,7 +53,6 @@ namespace DiscordChatExporter.Core.Models
         {
             get
             {
-                // Absolute value is used to deal with negative values
                 if (Math.Abs(PetaBytes) >= 1)
                     return PetaBytes;
 
diff --git a/DiscordChatExporter.Core.Models/Guild.cs b/DiscordChatExporter.Core.Models/Guild.cs
index 97c7b9f..0f31838 100644
--- a/DiscordChatExporter.Core.Models/Guild.cs
+++ b/DiscordChatExporter.Core.Models/Guild.cs
@@ -2,7 +2,7 @@
 {
     // https://discordapp.string.IsNullOrWhiteSpace(com/developers/docs/resources/guild#guild-object
 
-    public partial class Guild
+    public partial class Guild : IHasId
     {
         public string Id { get; }
 
diff --git a/DiscordChatExporter.Core.Models/IHasId.cs b/DiscordChatExporter.Core.Models/IHasId.cs
new file mode 100644
index 0000000..27ac643
--- /dev/null
+++ b/DiscordChatExporter.Core.Models/IHasId.cs
@@ -0,0 +1,7 @@
+namespace DiscordChatExporter.Core.Models
+{
+    public interface IHasId
+    {
+        string Id { get; }
+    }
+}
\ No newline at end of file
diff --git a/DiscordChatExporter.Core.Models/IdBasedEqualityComparer.cs b/DiscordChatExporter.Core.Models/IdBasedEqualityComparer.cs
new file mode 100644
index 0000000..1c77ad9
--- /dev/null
+++ b/DiscordChatExporter.Core.Models/IdBasedEqualityComparer.cs
@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+
+namespace DiscordChatExporter.Core.Models
+{
+    public partial class IdBasedEqualityComparer : IEqualityComparer<IHasId>
+    {
+        public bool Equals(IHasId? x, IHasId? y) => StringComparer.Ordinal.Equals(x?.Id, y?.Id);
+
+        public int GetHashCode(IHasId obj) => StringComparer.Ordinal.GetHashCode(obj.Id);
+    }
+
+    public partial class IdBasedEqualityComparer
+    {
+        public static IdBasedEqualityComparer Instance { get; } = new IdBasedEqualityComparer();
+    }
+}
\ No newline at end of file
diff --git a/DiscordChatExporter.Core.Models/Message.cs b/DiscordChatExporter.Core.Models/Message.cs
index 7fe2135..7deacdc 100644
--- a/DiscordChatExporter.Core.Models/Message.cs
+++ b/DiscordChatExporter.Core.Models/Message.cs
@@ -5,7 +5,7 @@ namespace DiscordChatExporter.Core.Models
 {
     // https://discordapp.com/developers/docs/resources/channel#message-object
 
-    public class Message
+    public class Message : IHasId
     {
         public string Id { get; }
 
diff --git a/DiscordChatExporter.Core.Models/Role.cs b/DiscordChatExporter.Core.Models/Role.cs
index 4eb1b20..5409f21 100644
--- a/DiscordChatExporter.Core.Models/Role.cs
+++ b/DiscordChatExporter.Core.Models/Role.cs
@@ -2,7 +2,7 @@
 {
     // https://discordapp.com/developers/docs/topics/permissions#role-object
 
-    public partial class Role
+    public partial class Role : IHasId
     {
         public string Id { get; }
 
diff --git a/DiscordChatExporter.Core.Models/User.cs b/DiscordChatExporter.Core.Models/User.cs
index ae33ba2..2114aac 100644
--- a/DiscordChatExporter.Core.Models/User.cs
+++ b/DiscordChatExporter.Core.Models/User.cs
@@ -4,7 +4,7 @@ namespace DiscordChatExporter.Core.Models
 {
     // https://discordapp.com/developers/docs/topics/permissions#role-object
 
-    public partial class User
+    public partial class User : IHasId
     {
         public string Id { get; }