diff --git a/lib/scsi-lowlevel.c b/lib/scsi-lowlevel.c
index b953e94..483dc89 100644
--- a/lib/scsi-lowlevel.c
+++ b/lib/scsi-lowlevel.c
@@ -1400,7 +1400,7 @@ scsi_cdb_read6(uint32_t lba, uint32_t xferlen, int blocksize)
 	int num_blocks;
 
 	num_blocks = xferlen/blocksize;
-	if (num_blocks > 265) {
+	if (num_blocks > 256) {
 		return NULL;
 	}