diff --git a/drivers/media/usb/dvb-usb/af9005.c b/drivers/media/usb/dvb-usb/af9005.c
index 0827bf3d4e8c7..13604e6acdb83 100644
--- a/drivers/media/usb/dvb-usb/af9005.c
+++ b/drivers/media/usb/dvb-usb/af9005.c
@@ -422,6 +422,10 @@ static int af9005_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[],
 		if (ret == 0)
 			ret = 2;
 	} else {
+		if (msg[0].len < 2) {
+			ret = -EOPNOTSUPP;
+			goto unlock;
+		}
 		/* write one or more registers */
 		reg = msg[0].buf[0];
 		addr = msg[0].addr;
@@ -431,6 +435,7 @@ static int af9005_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[],
 			ret = 1;
 	}
 
+unlock:
 	mutex_unlock(&d->i2c_mutex);
 	return ret;
 }