diff -u a/pri_internal.h b/pri_internal.h
--- a/pri_internal.h	2005-11-29 19:39:18.000000000 +0100
+++ b/pri_internal.h	2008-01-18 16:12:05.200685051 +0100
@@ -25,6 +25,7 @@
 #ifndef _PRI_INTERNAL_H
 #define _PRI_INTERNAL_H
 
+#include <stddef.h>
 #include <sys/time.h>
 
 struct pri_sched {