1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/isdn/hardware/mISDN/avmfritz.c b/drivers/isdn/hardware/mISDN/avmfritz.c
index 05ed4d0cb18b..c0b8c960ee3f 100644
--- a/drivers/isdn/hardware/mISDN/avmfritz.c
+++ b/drivers/isdn/hardware/mISDN/avmfritz.c
@@ -891,7 +891,7 @@ open_bchannel(struct fritzcard *fc, struct channel_req *rq)
 {
         struct bchannel         *bch;
 
-        if (rq->adr.channel > 2)
+        if (rq->adr.channel == 0 || rq->adr.channel > 2)
                 return -EINVAL;
         if (rq->protocol == ISDN_P_NONE)
                 return -EINVAL;