diff --git a/DiscordChatExporter/Models/Channel.cs b/DiscordChatExporter/Models/Channel.cs
index ff1b1902..43568d19 100644
--- a/DiscordChatExporter/Models/Channel.cs
+++ b/DiscordChatExporter/Models/Channel.cs
@@ -1,6 +1,6 @@
 namespace DiscordChatExporter.Models
 {
-    public class Channel
+    public partial class Channel
     {
         public string Id { get; }
 
@@ -23,4 +23,12 @@
             return Name;
         }
     }
+
+    public partial class Channel
+    {
+        public static Channel CreateDeletedChannel(string id)
+        {
+            return new Channel(id, "deleted-channel", null, ChannelType.GuildTextChat);
+        }
+    }
 }
\ No newline at end of file
diff --git a/DiscordChatExporter/Models/Role.cs b/DiscordChatExporter/Models/Role.cs
index a714f5e1..55b031cf 100644
--- a/DiscordChatExporter/Models/Role.cs
+++ b/DiscordChatExporter/Models/Role.cs
@@ -1,6 +1,6 @@
 namespace DiscordChatExporter.Models
 {
-    public class Role
+    public partial class Role
     {
         public string Id { get; }
 
@@ -17,4 +17,12 @@
             return Name;
         }
     }
+
+    public partial class Role
+    {
+        public static Role CreateDeletedRole(string id)
+        {
+            return new Role(id, "deleted-role");
+        }
+    }
 }
\ No newline at end of file
diff --git a/DiscordChatExporter/Services/DataService.cs b/DiscordChatExporter/Services/DataService.cs
index 578544e3..2597fe7e 100644
--- a/DiscordChatExporter/Services/DataService.cs
+++ b/DiscordChatExporter/Services/DataService.cs
@@ -121,7 +121,7 @@ namespace DiscordChatExporter.Services
             // Get role mentions
             var mentionedRoles = token["mention_roles"]
                 .Values<string>()
-                .Select(i => _roleCache.GetOrDefault(i) ?? new Role(i, "deleted-role"))
+                .Select(i => _roleCache.GetOrDefault(i) ?? Role.CreateDeletedRole(id))
                 .ToArray();
 
             // Get channel mentions
@@ -129,8 +129,7 @@ namespace DiscordChatExporter.Services
                 .Cast<Match>()
                 .Select(m => m.Groups[1].Value)
                 .ExceptBlank()
-                .Select(i => _channelCache.GetOrDefault(i) ??
-                             new Channel(i, "deleted-channel", null, ChannelType.GuildTextChat))
+                .Select(i => _channelCache.GetOrDefault(i) ?? Channel.CreateDeletedChannel(id))
                 .ToArray();
 
             return new Message(id, type, author, timeStamp, editedTimeStamp, content, attachments,
diff --git a/DiscordChatExporter/Services/ExportService.cs b/DiscordChatExporter/Services/ExportService.cs
index 43200adc..67e8e692 100644
--- a/DiscordChatExporter/Services/ExportService.cs
+++ b/DiscordChatExporter/Services/ExportService.cs
@@ -188,7 +188,7 @@ namespace DiscordChatExporter.Services
                 return ExportAsHtmlAsync(filePath, log, css);
             }
 
-            throw new NotImplementedException();
+            throw new ArgumentOutOfRangeException(nameof(format));
         }
     }