diff -r a2701af27fde -r a380cce7d6f0 lib/master.c
--- a/lib/master.c	Tue Apr 14 13:12:24 2015 -0400
+++ b/lib/master.c	Tue Apr 14 16:25:44 2015 -0400
@@ -607,15 +607,18 @@
 
 /****************************************************************************/
 
-void ecrt_master_send(ec_master_t *master)
-{
-    int ret;
-
-    ret = ioctl(master->fd, EC_IOCTL_SEND, NULL);
+size_t ecrt_master_send(ec_master_t *master)
+{
+    int ret;
+    size_t sent_bytes = 0;
+
+    ret = ioctl(master->fd, EC_IOCTL_SEND, &sent_bytes);
     if (EC_IOCTL_IS_ERROR(ret)) {
         fprintf(stderr, "Failed to send: %s\n",
                 strerror(EC_IOCTL_ERRNO(ret)));
     }
+
+    return sent_bytes;
 }
 
 /****************************************************************************/