Index: uspace/lib/c/include/offset.h
===================================================================
--- uspace/lib/c/include/offset.h	(revision 4805495a910f793f8918c13f029a38a5bb548154)
+++ uspace/lib/c/include/offset.h	(revision 3e828ea40985ce126affd5d7faa6ba679802b4db)
@@ -36,5 +36,11 @@
 #define _LIBC_OFFSET_H_
 
+#ifndef _HELENOS_SOURCE
+#error This file should only be included from HelenOS sources
+#endif
+
 #include <stdint.h>
+#include <_bits/decls.h>
+#include <_bits/off64_t.h>
 
 /* off64_t */
@@ -52,9 +58,10 @@
 #define PRIXOFF64 PRIX64
 
-/** Relative offset */
-typedef int64_t off64_t;
+__HELENOS_DECLS_BEGIN;
 
 /** Absolute offset */
 typedef uint64_t aoff64_t;
+
+__HELENOS_DECLS_END;
 
 #endif