diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
index 6f22ed0dab65..587cce57adae 100644
--- a/drivers/block/cciss.c
+++ b/drivers/block/cciss.c
@@ -2601,6 +2601,8 @@ static int fill_cmd(ctlr_info_t *h, CommandList_struct *c, __u8 cmd, void *buff,
 			c->Request.Timeout = 0;
 			c->Request.CDB[0] = BMIC_WRITE;
 			c->Request.CDB[6] = BMIC_CACHE_FLUSH;
+			c->Request.CDB[7] = (size >> 8) & 0xFF;
+			c->Request.CDB[8] = size & 0xFF;
 			break;
 		case TEST_UNIT_READY:
 			c->Request.CDBLen = 6;