diff --git a/assets/js/ticket.js b/assets/js/ticket.js
index 3495475..316ee34 100644
--- a/assets/js/ticket.js
+++ b/assets/js/ticket.js
@@ -1048,7 +1048,7 @@ function renderAttachments(attachments) {
         });
         const uploadDate = `<span class="ts-cell" data-ts="${lt.escHtml(att.uploaded_at)}" title="${lt.escHtml(uploadDateFormatted)}">${lt.time.ago(att.uploaded_at)}</span>`;
 
-        const isImage = /\.(png|jpe?g|gif|webp|svg|bmp)$/i.test(att.original_filename);
+        const isImage = /^image\//i.test(att.mime_type || '');
         const imgUrl  = `/api/download_attachment.php?id=${att.attachment_id}&inline=1`;
         const iconHtml = isImage
             ? `<a href="${imgUrl}" class="lt-lightbox-trigger" data-lightbox="ticket-attachments" title="${lt.escHtml(att.original_filename)}">