diff --git a/sys/dev/sio/sio.c b/sys/dev/sio/sio.c
index 476c967143ae..b44d516939d5 100644
--- a/sys/dev/sio/sio.c
+++ b/sys/dev/sio/sio.c
@@ -2923,7 +2923,7 @@ siocnprobe(cp)
 
 #ifdef __alpha__
 
-CONS_DRIVER(sio, NULL, NULL, NULL, siocngetc, siocncheckc, siocnputc);
+CONS_DRIVER(sio, NULL, NULL, NULL, siocngetc, siocncheckc, siocnputc, NULL);
 
 int
 siocnattach(port, speed)
diff --git a/sys/isa/sio.c b/sys/isa/sio.c
index 476c967143ae..b44d516939d5 100644
--- a/sys/isa/sio.c
+++ b/sys/isa/sio.c
@@ -2923,7 +2923,7 @@ siocnprobe(cp)
 
 #ifdef __alpha__
 
-CONS_DRIVER(sio, NULL, NULL, NULL, siocngetc, siocncheckc, siocnputc);
+CONS_DRIVER(sio, NULL, NULL, NULL, siocngetc, siocncheckc, siocnputc, NULL);
 
 int
 siocnattach(port, speed)