diff --git a/sys/dev/hyperv/vmbus/vmbus_br.c b/sys/dev/hyperv/vmbus/vmbus_br.c
index 99f4f8826b17..d9bd787a512e 100644
--- a/sys/dev/hyperv/vmbus/vmbus_br.c
+++ b/sys/dev/hyperv/vmbus/vmbus_br.c
@@ -26,6 +26,9 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
 #include <sys/param.h>
 #include <sys/lock.h>
 #include <sys/mutex.h>