diff --git a/lib/discordrb/webhooks/builder.rb b/lib/discordrb/webhooks/builder.rb
index 3e879ca32..4e3ac1403 100644
--- a/lib/discordrb/webhooks/builder.rb
+++ b/lib/discordrb/webhooks/builder.rb
@@ -83,7 +83,7 @@ def to_json_hash
         avatar_url: @avatar_url,
         tts: @tts,
         embeds: @embeds.map(&:to_hash),
-        allowed_mentions: @allowed_mentions
+        allowed_mentions: @allowed_mentions&.to_hash
       }
     end
 
@@ -95,7 +95,7 @@ def to_multipart_hash
         avatar_url: @avatar_url,
         tts: @tts,
         file: @file,
-        allowed_mentions: @allowed_mentions
+        allowed_mentions: @allowed_mentions&.to_hash
       }
     end
   end