diff --git a/hw/bsp/mimxrt1060_evk/mimxrt1060_evk.c b/hw/bsp/mimxrt1060_evk/mimxrt1060_evk.c
index 1042bcfe7..6fb00b9b7 100644
--- a/hw/bsp/mimxrt1060_evk/mimxrt1060_evk.c
+++ b/hw/bsp/mimxrt1060_evk/mimxrt1060_evk.c
@@ -49,6 +49,7 @@
 #define UART_RX_PINMUX        IOMUXC_GPIO_AD_B0_13_LPUART1_RX
 #define UART_TX_PINMUX        IOMUXC_GPIO_AD_B0_12_LPUART1_TX
 
+// needed by fsl_flexspi_nor_boot
 const uint8_t dcd_data[] = { 0x00 };
 
 void board_init(void)
diff --git a/hw/bsp/teensy_40/teensy40.c b/hw/bsp/teensy_40/teensy40.c
index 30fdedd27..85501df11 100644
--- a/hw/bsp/teensy_40/teensy40.c
+++ b/hw/bsp/teensy_40/teensy40.c
@@ -49,6 +49,7 @@
 #define UART_RX_PINMUX        IOMUXC_GPIO_AD_B0_03_LPUART6_RX  // D0
 #define UART_TX_PINMUX        IOMUXC_GPIO_AD_B0_02_LPUART6_TX  // D1
 
+// needed by fsl_flexspi_nor_boot
 const uint8_t dcd_data[] = { 0x00 };
 
 void board_init(void)