Index: io.c
--- io.c.orig
+++ io.c
@@ -15,6 +15,7 @@ Please read the file COPYRIGHT for further details.
 #include <sys/bsdtypes.h>
 #endif
 #include <errno.h>
+#include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>