diff --git a/boards/mro/x21/nuttx-config/nsh/defconfig b/boards/mro/x21/nuttx-config/nsh/defconfig
index ef45ba3e22..1d9b748c6b 100644
--- a/boards/mro/x21/nuttx-config/nsh/defconfig
+++ b/boards/mro/x21/nuttx-config/nsh/defconfig
@@ -79,11 +79,9 @@ CONFIG_IDLETHREAD_STACKSIZE=750
 CONFIG_LIBC_FLOATINGPOINT=y
 CONFIG_LIBC_LONG_LONG=y
 CONFIG_LIBC_STRERROR=y
-CONFIG_MAX_WDOGPARMS=2
 CONFIG_MEMSET_64BIT=y
 CONFIG_MEMSET_OPTSPEED=y
 CONFIG_MMCSD=y
-CONFIG_MMCSD_MULTIBLOCK_DISABLE=y
 CONFIG_MMCSD_SDIO=y
 CONFIG_MMCSD_SDIOWAIT_WRCOMPLETE=y
 CONFIG_MM_REGIONS=2
@@ -114,7 +112,6 @@ CONFIG_NSH_STRERROR=y
 CONFIG_NSH_VARS=y
 CONFIG_PIPES=y
 CONFIG_PREALLOC_TIMERS=50
-CONFIG_PREALLOC_WDOGS=50
 CONFIG_PRIORITY_INHERITANCE=y
 CONFIG_PTHREAD_MUTEX_ROBUST=y
 CONFIG_PTHREAD_STACK_MIN=512
@@ -197,7 +194,6 @@ CONFIG_STM32_WWDG=y
 CONFIG_SYSTEM_CDCACM=y
 CONFIG_SYSTEM_NSH=y
 CONFIG_TASK_NAME_SIZE=24
-CONFIG_TIME_EXTENDED=y
 CONFIG_UART4_BAUD=57600
 CONFIG_UART4_RXBUFSIZE=300
 CONFIG_UART4_RXDMA=y
diff --git a/boards/mro/x21/nuttx-config/scripts/script.ld b/boards/mro/x21/nuttx-config/scripts/script.ld
index 0d19229c01..db27829f89 100644
--- a/boards/mro/x21/nuttx-config/scripts/script.ld
+++ b/boards/mro/x21/nuttx-config/scripts/script.ld
@@ -89,11 +89,6 @@ SECTIONS
 		*(.gnu.linkonce.r.*)
 		_etext = ABSOLUTE(.);
 
-		/*
-		 * This is a hack to make the newlib libm __errno() call
-		 * use the NuttX get_errno_ptr() function.
-		 */
-		__errno = get_errno_ptr;
 	} > flash
 
 	/*
diff --git a/boards/mro/x21/src/can.c b/boards/mro/x21/src/can.c
index 42c04b2900..5a32d62832 100644
--- a/boards/mro/x21/src/can.c
+++ b/boards/mro/x21/src/can.c
@@ -50,7 +50,7 @@
 #include <arch/board/board.h>
 
 #include "chip.h"
-#include "up_arch.h"
+#include "arm_arch.h"
 
 #include "stm32.h"
 #include "stm32_can.h"
diff --git a/boards/mro/x21/src/init.c b/boards/mro/x21/src/init.c
index 711e1eb028..fa0cc4c7e7 100644
--- a/boards/mro/x21/src/init.c
+++ b/boards/mro/x21/src/init.c
@@ -81,7 +81,7 @@
  ****************************************************************************/
 
 /*
- * Ideally we'd be able to get these from up_internal.h,
+ * Ideally we'd be able to get these from arm_internal.h,
  * but since we want to be able to disable the NuttX use
  * of leds for system indication at will and there is no
  * separate switch, we need to build independent of the
diff --git a/boards/mro/x21/src/led.c b/boards/mro/x21/src/led.c
index 86b3333c06..8a70a4cb29 100644
--- a/boards/mro/x21/src/led.c
+++ b/boards/mro/x21/src/led.c
@@ -47,7 +47,7 @@
 #include "board_config.h"
 
 /*
- * Ideally we'd be able to get these from up_internal.h,
+ * Ideally we'd be able to get these from arm_internal.h,
  * but since we want to be able to disable the NuttX use
  * of leds for system indication at will and there is no
  * separate switch, we need to build independent of the
diff --git a/boards/mro/x21/src/usb.c b/boards/mro/x21/src/usb.c
index 0359001d77..6fbea86a0b 100644
--- a/boards/mro/x21/src/usb.c
+++ b/boards/mro/x21/src/usb.c
@@ -51,7 +51,7 @@
 #include <nuttx/usb/usbdev.h>
 #include <nuttx/usb/usbdev_trace.h>
 
-#include <up_arch.h>
+#include <arm_arch.h>
 #include <stm32.h>
 
 #include "board_config.h"