diff --git a/modules/helpdesk/pages/helpdesk/ticket-file-data().php b/modules/helpdesk/pages/helpdesk/ticket-file-data().php
index 55839ef..e4f54aa 100644
--- a/modules/helpdesk/pages/helpdesk/ticket-file-data().php
+++ b/modules/helpdesk/pages/helpdesk/ticket-file-data().php
@@ -79,7 +79,19 @@ if (strlen($data) > $maxFileSize) {
     return;
 }
 
+// Ensure filename has an extension — derive from content if missing
 $displayFilename = $filename !== '' ? $filename : 'attachment-' . $entryNo;
+if (!str_contains($displayFilename, '.')) {
+    $ext = match (true) {
+        str_starts_with($data, "\x89PNG") => '.png',
+        str_starts_with($data, "\xFF\xD8\xFF") => '.jpg',
+        str_starts_with($data, "GIF8") => '.gif',
+        str_starts_with($data, "%PDF") => '.pdf',
+        str_starts_with($data, "PK\x03\x04") => '.zip',
+        default => '',
+    };
+    $displayFilename .= $ext;
+}
 
 header('X-Content-Type-Options: nosniff');
 header('Content-Security-Policy: sandbox');