diff --git a/controllers/EditAsset.php b/controllers/EditAsset.php
index a794fd48..3b99a524 100644
--- a/controllers/EditAsset.php
+++ b/controllers/EditAsset.php
@@ -118,7 +118,7 @@ class EditAsset extends HTMLController
 
 			// Does the thumbnail exist on disk? If not, use an url to generate it.
 			if (!$filename || !file_exists(THUMBSDIR . '/' . $subdir . '/' . $filename))
-				$thumb_url = BASEURL . '/thumbnail/' . $image->getId() . '/' . $thumb['width'] . 'x' . $thumb['height'] . $thumb['suffix'] . '/';
+				$thumb_url = BASEURL . '/thumbnail/' . $image->getId() . '/' . $thumb['width'] . 'x' . $thumb['height'] . ($thumb['suffix'] ?? '') . '/';
 			else
 				$thumb_url = THUMBSURL . '/' . $subdir . '/' . $filename;