diff -Naur delay-1.6.orig/delay.c delay-1.6/delay.c
--- delay-1.6.orig/delay.c	2002-02-09 16:26:39.000000000 +0100
+++ delay-1.6/delay.c	2015-03-15 18:32:29.980536243 +0100
@@ -17,6 +17,7 @@
 */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <time.h>
 #include <sys/time.h>
 #include <unistd.h>