Index: src/OFFile.m
==================================================================
--- src/OFFile.m
+++ src/OFFile.m
@@ -13,11 +13,13 @@
  * file.
  */
 
 #include "config.h"
 
-#define _LARGEFILE64_SOURCE
+#ifndef _LARGEFILE64_SOURCE
+# define _LARGEFILE64_SOURCE
+#endif
 
 #include <errno.h>
 
 #ifdef HAVE_FCNTL_H
 # include <fcntl.h>

Index: src/OFFileIRIHandler.m
==================================================================
--- src/OFFileIRIHandler.m
+++ src/OFFileIRIHandler.m
@@ -13,11 +13,13 @@
  * file.
  */
 
 #include "config.h"
 
-#define _LARGEFILE64_SOURCE
+#ifndef _LARGEFILE64_SOURCE
+# define _LARGEFILE64_SOURCE
+#endif
 
 #include <errno.h>
 #include <math.h>
 
 #ifdef HAVE_DIRENT_H