diff --git a/src/Responders/MessageEditedResponder.cs b/src/Responders/MessageEditedResponder.cs
index 3e42177..64e76e0 100644
--- a/src/Responders/MessageEditedResponder.cs
+++ b/src/Responders/MessageEditedResponder.cs
@@ -67,7 +67,12 @@ public class MessageEditedResponder : IResponder<IMessageUpdate>
             return new ArgumentNullError(nameof(gatewayEvent.ID));
         }
 
-        if (gatewayEvent.Author.Value.IsBot.OrDefault(false))
+        if (!gatewayEvent.Author.IsDefined(out var author))
+        {
+            return new ArgumentNullError(nameof(gatewayEvent.Author));
+        }
+
+        if (author.IsBot.OrDefault(false))
         {
             return Result.FromSuccess();
         }