--- signal.c
+++ signal.c
@@ -1701,7 +1701,7 @@ sys_kill(tcp)
 struct tcb *tcp;
 {
 	if (entering(tcp)) {
-		tprintf("%ld, %s", tcp->u_arg[0], signame(tcp->u_arg[1]));
+		tprintf("%d, %s", (pid_t)tcp->u_arg[0], signame(tcp->u_arg[1]));
 	}
 	return 0;
 }