diff --git a/hw/scsi/scsi-generic.c b/hw/scsi/scsi-generic.c
index 92cce20a4d..bc30bf8bad 100644
--- a/hw/scsi/scsi-generic.c
+++ b/hw/scsi/scsi-generic.c
@@ -322,11 +322,17 @@ static void scsi_read_complete(void * opaque, int ret)
     if (r->req.cmd.buf[0] == READ_CAPACITY_10 &&
         (ldl_be_p(&r->buf[0]) != 0xffffffffU || s->max_lba == 0)) {
         s->blocksize = ldl_be_p(&r->buf[4]);
-        s->max_lba = ldl_be_p(&r->buf[0]) & 0xffffffffULL;
+        BlockBackend *blk = s->conf.blk;
+        BlockDriverState *bs = blk_bs(blk);
+        s->max_lba = bs->total_sectors - 1;
+        stl_be_p(&r->buf[0], s->max_lba);
     } else if (r->req.cmd.buf[0] == SERVICE_ACTION_IN_16 &&
                (r->req.cmd.buf[1] & 31) == SAI_READ_CAPACITY_16) {
         s->blocksize = ldl_be_p(&r->buf[8]);
-        s->max_lba = ldq_be_p(&r->buf[0]);
+        BlockBackend *blk = s->conf.blk;
+        BlockDriverState *bs = blk_bs(blk);
+        s->max_lba = bs->total_sectors - 1;
+        stq_be_p(&r->buf[0], s->max_lba);
     }
 
     /*