--- 9wm-1.2.orig/main.c
+++ 9wm-1.2/main.c
@@ -1,4 +1,5 @@
 /* Copyright (c) 1994-1996 David Hogan, see README for licence details */
+#include <stdlib.h>
 #include <stdio.h>
 #include <signal.h>
 #include <errno.h>