diff --git a/qrexec-lib/unpack.c b/qrexec-lib/unpack.c
index 3bc9dda..df0732e 100644
--- a/qrexec-lib/unpack.c
+++ b/qrexec-lib/unpack.c
@@ -27,9 +27,11 @@ void send_status_and_crc(int code, const char *last_filename);
 #ifndef __O_TMPFILE
 #define __O_TMPFILE 020000000
 #endif
+#ifndef O_TMPFILE
 /* a horrid kludge trying to make sure that this will fail on old kernels */
 #define O_TMPFILE (__O_TMPFILE | O_DIRECTORY)
 #define O_TMPFILE_MASK (__O_TMPFILE | O_DIRECTORY | O_CREAT)
+#endif
 
 void do_exit(int code, const char *last_filename)
 {