diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index e166045..fc79cf4 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -586,7 +586,7 @@
 				   struct ide_atapi_pc *pc, struct request *rq,
 				   u8 opcode)
 {
-	unsigned int length = blk_rq_sectors(rq);
+	unsigned int length = blk_rq_sectors(rq) / (tape->blk_size >> 9);
 
 	ide_init_pc(pc);
 	put_unaligned(cpu_to_be32(length), (unsigned int *) &pc->c[1]);