diff --git a/src/ringbuf.c b/src/ringbuf.c
index bc10fa1..4fc6c6c 100644
--- a/src/ringbuf.c
+++ b/src/ringbuf.c
@@ -4,6 +4,9 @@
  *
  * Copyright (C) 2020 Facebook, Inc.
  */
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
 #include <stdlib.h>
 #include <stdio.h>
 #include <errno.h>