diff --git a/internal/matrixbot/bot.go b/internal/matrixbot/bot.go
index 8ac8ea5..e5c6b2f 100644
--- a/internal/matrixbot/bot.go
+++ b/internal/matrixbot/bot.go
@@ -207,6 +207,13 @@ func (b *Bot) sendReply(ctx context.Context, evt *event.Event, response string)
 		content.FormattedBody = formatted
 	}
 
+	original := evt.Content.AsMessage()
+	if original != nil && original.RelatesTo != nil && original.RelatesTo.GetThreadParent() != "" {
+		content.SetThread(evt)
+	} else {
+		content.SetReply(evt)
+	}
+
 	_, err := b.client.SendMessageEvent(ctx, evt.RoomID, event.EventMessage, content)
 	return err
 }