1 files changed, 4 insertions, 0 deletions
diff --git a/drivers.c b/drivers.c
index ad480fa3..98a24854 100644
--- a/drivers.c
+++ b/drivers.c
@@ -2,6 +2,10 @@
  * This file is Copyright (c) 2010 by the GPSD project
  * BSD terms apply: see the file COPYING in the distribution root for details.
  */
+
+/* for vsnprintf() FreeBSD wants __ISO_C_VISIBLE >= 1999 */
+#define __ISO_C_VISIBLE 1999
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdbool.h>