X-Git-Url: http://git.alex.org.uk

diff --git a/lfs.h b/lfs.h
index 8f90f81..480d6bf 100644
--- a/lfs.h
+++ b/lfs.h
@@ -2,9 +2,15 @@
 #define LFS_H
 
 #include "config.h"
-#ifdef NBD_LFS
+#if NBD_LFS
 #define _FILE_OFFSET_BITS 64
+#ifndef _LARGEFILE_SOURCE
 #define _LARGEFILE_SOURCE
+#endif
+#ifdef HAVE_SYNC_FILE_RANGE
+#define USE_SYNC_FILE_RANGE
+#define _GNU_SOURCE
+#endif /* HAVE_SYNC_FILE_RANGE */
 #endif /* NBD_LFS */
 
 #endif /* LFS_H */