diff --git a/common.php b/common.php
index 99d089e..7290ad0 100644
--- a/common.php
+++ b/common.php
@@ -417,6 +417,7 @@ function baseclassofdrive($d = null)
 
 function extendShow_diskenv($drive)
 {
+    if (!$drive) return [];
     return $drive->ext_show_innerenv();
 }