--- xflock4	2014-02-10 11:20:35.423079298 +0100
+++ xflock4.new	2014-02-10 11:20:27.515078842 +0100
@@ -35,7 +35,8 @@
 # else run another access locking utility, if installed
 for lock_cmd in \
   "xlock -mode blank" \
-  "slock"
+  "slock" \
+  "alock -bg blank -auth pam"
   do
     set -- $lock_cmd
     if command -v -- $1 >/dev/null 2>&1; then