diff --git a/src-ofd/Lukko/OFD.hsc b/src-ofd/Lukko/OFD.hsc
index b4b9074..82e1170 100644
--- a/src-ofd/Lukko/OFD.hsc
+++ b/src-ofd/Lukko/OFD.hsc
@@ -33,6 +33,7 @@ module Lukko.OFD (
     hUnlock,
     ) where
 
+#define _FILE_OFFSET_BITS 64
 #define _GNU_SOURCE
 #include <unistd.h>