diff --git a/fmacros.h b/fmacros.h
index 7c9b91ae..986776f2 100644
--- a/fmacros.h
+++ b/fmacros.h
@@ -3,5 +3,7 @@
 
 #define _BSD_SOURCE
 #define _XOPEN_SOURCE
+#define _LARGEFILE_SOURCE
+#define _FILE_OFFSET_BITS 64
 
 #endif