--- sl.c.orig	2003-09-07 14:20:29.000000000 +0900
+++ sl.c	2003-09-07 14:21:11.000000000 +0900
@@ -164,6 +164,7 @@
     signal(SIGINT, end_proc);
 #else
+    signal(SIGTSTP, SIG_IGN);
     signal(SIGINT, SIG_IGN);
     PASSNUM = (int)(drand48() * 20.0) + 10;
     if (drand48() > 0.5) {
       ONEDIREC = 1;