diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c
index 5d997a3..2a3973a 100644
--- a/drivers/firewire/core-cdev.c
+++ b/drivers/firewire/core-cdev.c
@@ -1637,8 +1637,7 @@ static int dispatch_ioctl(struct client *client,
 	    _IOC_SIZE(cmd) > sizeof(buffer))
 		return -ENOTTY;
 
-	if (_IOC_DIR(cmd) == _IOC_READ)
-		memset(&buffer, 0, _IOC_SIZE(cmd));
+	memset(&buffer, 0, sizeof(buffer));
 
 	if (_IOC_DIR(cmd) & _IOC_WRITE)
 		if (copy_from_user(&buffer, arg, _IOC_SIZE(cmd)))