models/Image.php

@@ -158,7 +158,8 @@ class Image extends Asset
 		}
 
 		return Registry::get('db')->query('
-			DELETE FROM assets_thumbs
+			UPDATE assets_thumbs
+			SET filename = NULL
 			WHERE id_asset = {int:id_asset}',
 			['id_asset' => $this->id_asset]);
 	}