diff --git a/libavdevice/bktr.c b/libavdevice/bktr.c
index 942f58dd9e..c63d79ea28 100644
--- a/libavdevice/bktr.c
+++ b/libavdevice/bktr.c
@@ -25,6 +25,7 @@
  */
 
 #define _BSD_SOURCE 1
+#define _NETBSD_SOURCE
 
 #include "libavformat/avformat.h"
 #if HAVE_DEV_BKTR_IOCTL_METEOR_H && HAVE_DEV_BKTR_IOCTL_BT848_H