diff -up expect5.45/example/passmass.orig expect5.45/example/passmass
--- expect5.45/example/passmass.orig	2011-09-06 13:04:41.439875491 +0200
+++ expect5.45/example/passmass	2011-09-06 13:04:54.663874571 +0200
@@ -178,7 +178,7 @@ for {set i 0} {$i<$argc} {incr i} {
     }
 
     if ($su) {
-	send "su -\r"
+	send "/bin/su -\r"
 	expect -nocase "password:"
 	send "$password(old)\r"
 	expect "# "