diff --git a/drivers/misc/mediatek/typec/tcpc/tcpc_mt6360.c b/drivers/misc/mediatek/typec/tcpc/tcpc_mt6360.c
index 36b9d7d4289e..aafc1933692f 100644
--- a/drivers/misc/mediatek/typec/tcpc/tcpc_mt6360.c
+++ b/drivers/misc/mediatek/typec/tcpc/tcpc_mt6360.c
@@ -2121,9 +2121,9 @@ static int mt6360_set_bist_carrier_mode(struct tcpc_device *tcpc, u8 pattern)
 	return 0;
 }
 
-/* message header (2byte) + data object (7*4) */
+/* transmit count (1byte) + message header (2byte) + data object (7*4) */
 #define MT6360_TRANSMIT_MAX_SIZE \
-	(sizeof(u16) + sizeof(u32) * 7)
+	(1 + sizeof(u16) + sizeof(u32) * 7)
 
 #ifdef CONFIG_USB_PD_RETRY_CRC_DISCARD
 static int mt6360_retransmit(struct tcpc_device *tcpc)
diff --git a/drivers/misc/mediatek/typec/tcpc/tcpc_mt6362.c b/drivers/misc/mediatek/typec/tcpc/tcpc_mt6362.c
index 779645b5cbb2..2fe7ba7c8279 100644
--- a/drivers/misc/mediatek/typec/tcpc/tcpc_mt6362.c
+++ b/drivers/misc/mediatek/typec/tcpc/tcpc_mt6362.c
@@ -1576,8 +1576,8 @@ static int mt6362_get_message(struct tcpc_device *tcpc, u32 *payload,
 	return ret;
 }
 
-/* message header (2byte) + data object (7*4) */
-#define MT6362_TRANSMIT_MAX_SIZE	(sizeof(u16) + sizeof(u32) * 7)
+/* transmit count (1byte) + message header (2byte) + data object (7*4) */
+#define MT6362_TRANSMIT_MAX_SIZE	(1 + sizeof(u16) + sizeof(u32) * 7)
 
 static int mt6362_transmit(struct tcpc_device *tcpc,
 			   enum tcpm_transmit_type type, u16 header,