$FreeBSD$

--- src/v17tx.c
+++ src/v17tx.c
@@ -39,6 +39,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <math.h>
+#include <tgmath.h>
 
 #include "spandsp/telephony.h"
 #include "spandsp/logging.h"