diff --git a/drivers/mfd/qnap-mcu.c b/drivers/mfd/qnap-mcu.c
index 8de974ddac3e..93a3dd93404d 100644
--- a/drivers/mfd/qnap-mcu.c
+++ b/drivers/mfd/qnap-mcu.c
@@ -56,6 +56,7 @@ struct qnap_mcu_reply {
  * @reply:	Reply data structure
  * @variant:	Device variant specific information
  * @version:	MCU firmware version
+ * @rx:		Receive buffer the reply is assembled in
  */
 struct qnap_mcu {
 	struct serdev_device *serdev;
@@ -63,6 +64,7 @@ struct qnap_mcu {
 	struct qnap_mcu_reply reply;
 	const struct qnap_mcu_variant *variant;
 	u8 version[QNAP_MCU_VERSION_LEN];
+	u8 rx[QNAP_MCU_RX_BUFFER_SIZE];
 };
 
 /*
@@ -214,19 +216,18 @@ int qnap_mcu_exec(struct qnap_mcu *mcu,
 		  const u8 *cmd_data, size_t cmd_data_size,
 		  u8 *reply_data, size_t reply_data_size)
 {
-	unsigned char rx[QNAP_MCU_RX_BUFFER_SIZE];
 	size_t length = reply_data_size + QNAP_MCU_CHECKSUM_SIZE;
 	struct qnap_mcu_reply *reply = &mcu->reply;
 	int ret = 0;
 
-	if (length > sizeof(rx)) {
+	if (length > sizeof(mcu->rx)) {
 		dev_err(&mcu->serdev->dev, "expected data too big for receive buffer");
 		return -EINVAL;
 	}
 
 	guard(mutex)(&mcu->bus_lock);
 
-	reply->data = rx;
+	reply->data = mcu->rx;
 	reply->length = length;
 	reply->received = 0;
 	reinit_completion(&reply->done);
@@ -242,15 +243,15 @@ int qnap_mcu_exec(struct qnap_mcu *mcu,
 		return -ETIMEDOUT;
 	}
 
-	if (!qnap_mcu_verify_checksum(rx, reply->received)) {
+	if (!qnap_mcu_verify_checksum(mcu->rx, reply->received)) {
 		dev_err(&mcu->serdev->dev, "Invalid Checksum received from controller\n");
 		return -EPROTO;
 	}
 
-	if (qnap_mcu_reply_is_any_error(mcu, rx, reply->received))
+	if (qnap_mcu_reply_is_any_error(mcu, mcu->rx, reply->received))
 		return -EPROTO;
 
-	memcpy(reply_data, rx, reply_data_size);
+	memcpy(reply_data, mcu->rx, reply_data_size);
 
 	return 0;
 }