diff --git a/UPGRADE b/UPGRADE
index 44f89f665..1b04e6095 100644
--- a/UPGRADE
+++ b/UPGRADE
@@ -40,6 +40,10 @@ o Upgrading from a version prior to 1.6:
     default, non-tty case, the timestamp on the directory itself
     is used.
 
+    Also, the temporary file used by visudo is now /etc/sudoers.tmp
+    since some versions of vipw on systems with shadow passwords use
+    /etc/stmp for the temporary shadow file.
+
 o Upgrading from a version prior to 1.5:
 
     By default, sudo expects the sudoers file to be mode 0440 and