diff --git a/configs/firefly-rk3399_defconfig b/configs/firefly-rk3399_defconfig
index a378706..5475172 100644
--- a/configs/firefly-rk3399_defconfig
+++ b/configs/firefly-rk3399_defconfig
@@ -61,6 +61,7 @@
 CONFIG_RNG_ROCKCHIP=y
 CONFIG_BAUDRATE=1500000
 CONFIG_DEBUG_UART_SHIFT=2
+CONFIG_SYS_NS16550_MEM32=y
 CONFIG_SYSRESET=y
 CONFIG_USB=y
 CONFIG_USB_XHCI_HCD=y