diff --git a/zupdate/sysupdate b/zupdate/sysupdate
index cfa2884..b75fdcc 100755
--- a/zupdate/sysupdate
+++ b/zupdate/sysupdate
@@ -2,7 +2,9 @@
 
 linuxpkgnames=""
 
-lock_file=/tmp/sysupdate.lock
+[ -z "$TMPDIR" ] && TMPDIR=/tmp
+
+lock_file="$TMPDIR/sysupdate.lock"
 
 get_running_programs()
 {