diff --git a/block/blk-core.c b/block/blk-core.c
index fe0d1390b74..e6fdb288be6 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -173,7 +173,7 @@ void blk_dump_rq_flags(struct request *rq, char *msg)
 
 	if (blk_pc_request(rq)) {
 		printk(KERN_INFO "  cdb: ");
-		for (bit = 0; bit < sizeof(rq->cmd); bit++)
+		for (bit = 0; bit < BLK_MAX_CDB; bit++)
 			printk("%02x ", rq->cmd[bit]);
 		printk("\n");
 	}
diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
index fe9df38f62c..68e7f19dc03 100644
--- a/drivers/ide/ide-cd.c
+++ b/drivers/ide/ide-cd.c
@@ -782,7 +782,7 @@ static ide_startstop_t cdrom_start_seek_continuation(ide_drive_t *drive)
 
 	sector_div(frame, queue_hardsect_size(drive->queue) >> SECTOR_BITS);
 
-	memset(rq->cmd, 0, sizeof(rq->cmd));
+	memset(rq->cmd, 0, BLK_MAX_CDB);
 	rq->cmd[0] = GPCMD_SEEK;
 	put_unaligned(cpu_to_be32(frame), (unsigned int *) &rq->cmd[2]);
 
@@ -1694,7 +1694,7 @@ static int ide_cdrom_prep_fs(struct request_queue *q, struct request *rq)
 	long block = (long)rq->hard_sector / (hard_sect >> 9);
 	unsigned long blocks = rq->hard_nr_sectors / (hard_sect >> 9);
 
-	memset(rq->cmd, 0, sizeof(rq->cmd));
+	memset(rq->cmd, 0, BLK_MAX_CDB);
 
 	if (rq_data_dir(rq) == READ)
 		rq->cmd[0] = GPCMD_READ_10;
diff --git a/drivers/ide/ide-cd_verbose.c b/drivers/ide/ide-cd_verbose.c
index 6ed7ca07133..6490a2dea96 100644
--- a/drivers/ide/ide-cd_verbose.c
+++ b/drivers/ide/ide-cd_verbose.c
@@ -326,7 +326,7 @@ void ide_cd_log_error(const char *name, struct request *failed_command,
 
 		printk(KERN_ERR "  The failed \"%s\" packet command "
 				"was: \n  \"", s);
-		for (i = 0; i < sizeof(failed_command->cmd); i++)
+		for (i = 0; i < BLK_MAX_CDB; i++)
 			printk(KERN_CONT "%02x ", failed_command->cmd[i]);
 		printk(KERN_CONT "\"\n");
 	}