diff --git a/drivers/char/ipmi/ipmi_bt_sm.c b/drivers/char/ipmi/ipmi_bt_sm.c
index 58dcdee1cd71..0030cd8e2e95 100644
--- a/drivers/char/ipmi/ipmi_bt_sm.c
+++ b/drivers/char/ipmi/ipmi_bt_sm.c
@@ -165,7 +165,7 @@ static int bt_start_transaction(struct si_sm_data *bt,
 {
 	unsigned int i;
 
-	if ((size < 2) || (size > IPMI_MAX_MSG_LENGTH))
+	if ((size < 2) || (size > (IPMI_MAX_MSG_LENGTH - 2)))
 	       return -1;
 
 	if ((bt->state != BT_STATE_IDLE) && (bt->state != BT_STATE_HOSED))