Index: usr.sbin/burncd/burncd.c
===================================================================
--- usr.sbin/burncd/burncd.c	(revision 225704)
+++ usr.sbin/burncd/burncd.c	(working copy)
@@ -159,8 +159,16 @@
 	if ((fd = open(dev, O_RDWR, 0)) < 0)
 		err(EX_NOINPUT, "open(%s)", dev);
 
-	if (ioctl(fd, CDRIOCGETBLOCKSIZE, &saved_block_size) < 0)
-		err(EX_IOERR, "ioctl(CDRIOCGETBLOCKSIZE)");
+	if (ioctl(fd, CDRIOCGETBLOCKSIZE, &saved_block_size) < 0) {
+		if (errno == ENOTTY)
+			errx(EX_IOERR,
+			    "device provided not an acd(4) device: %s.\n\n"
+			    "Please verify that your kernel is built with "
+			    "acd(4) and the beforementioned device is "
+			    "supported by acd(4).", dev);
+		else
+			err(EX_IOERR, "ioctl(CDRIOCGETBLOCKSIZE)");
+	}
 
 	if (ioctl(fd, CDRIOCWRITESPEED, &speed) < 0)
 		err(EX_IOERR, "ioctl(CDRIOCWRITESPEED)");