diff --git a/ports/mimxrt10xx/Makefile b/ports/mimxrt10xx/Makefile
index 5a8ac51fcf..8e83fb53b8 100644
--- a/ports/mimxrt10xx/Makefile
+++ b/ports/mimxrt10xx/Makefile
@@ -92,7 +92,7 @@ else
   #CFLAGS += -flto -flto-partition=none
 endif
 
-CFLAGS += $(INC) -ggdb -Wall -Werror -std=gnu11 -nostdlib -fshort-enums $(BASE_CFLAGS) $(CFLAGS_MOD) $(COPT)
+CFLAGS += $(INC) -ggdb -Wall -Werror -std=gnu11 -nostdlib -fshort-enums $(BASE_CFLAGS) $(CFLAGS_MOD) $(COPT) -Werror=missing-prototypes
 
 # TODO: add these when -Werror is applied
 # Disable some warnings, as do most ports. NXP SDK causes undef, tinyusb causes cast-align
@@ -148,7 +148,7 @@ SRC_SDK := \
 	system_$(CHIP_FAMILY).c \
 
 SRC_SDK := $(addprefix sdk/devices/$(CHIP_FAMILY)/, $(SRC_SDK))
-$(addprefix $(BUILD)/, $(SRC_SDK:.c=.o)): CFLAGS += -Wno-undef
+$(addprefix $(BUILD)/, $(SRC_SDK:.c=.o)): CFLAGS += -Wno-undef -Wno-missing-prototypes
 
 SRC_C += \
 	background.c \
diff --git a/ports/mimxrt10xx/common-hal/analogio/AnalogIn.c b/ports/mimxrt10xx/common-hal/analogio/AnalogIn.c
index 5e7bb82c77..2d809c258c 100644
--- a/ports/mimxrt10xx/common-hal/analogio/AnalogIn.c
+++ b/ports/mimxrt10xx/common-hal/analogio/AnalogIn.c
@@ -26,6 +26,7 @@
  */
 
 #include "common-hal/analogio/AnalogIn.h"
+#include "shared-bindings/analogio/AnalogIn.h"
 #include "shared-bindings/microcontroller/Pin.h"
 
 #include <string.h>
diff --git a/ports/mimxrt10xx/common-hal/busio/I2C.h b/ports/mimxrt10xx/common-hal/busio/I2C.h
index 789f01a5f5..6b37255fe3 100644
--- a/ports/mimxrt10xx/common-hal/busio/I2C.h
+++ b/ports/mimxrt10xx/common-hal/busio/I2C.h
@@ -41,4 +41,6 @@ typedef struct {
     const mcu_periph_obj_t *sda;
 } busio_i2c_obj_t;
 
+void i2c_reset(void);
+
 #endif // MICROPY_INCLUDED_MIMXRT10XX_COMMON_HAL_BUSIO_I2C_H
diff --git a/ports/mimxrt10xx/common-hal/busio/UART.c b/ports/mimxrt10xx/common-hal/busio/UART.c
index 16c4ba77e4..7933975322 100644
--- a/ports/mimxrt10xx/common-hal/busio/UART.c
+++ b/ports/mimxrt10xx/common-hal/busio/UART.c
@@ -65,7 +65,7 @@ static void config_periph_pin(const mcu_periph_obj_t *periph) {
         | IOMUXC_SW_PAD_CTL_PAD_SRE(0));
 }
 
-void LPUART_UserCallback(LPUART_Type *base, lpuart_handle_t *handle, status_t status, void *user_data) {
+STATIC void LPUART_UserCallback(LPUART_Type *base, lpuart_handle_t *handle, status_t status, void *user_data) {
     busio_uart_obj_t *self = (busio_uart_obj_t *)user_data;
 
     if (status == kStatus_LPUART_RxIdle) {
diff --git a/ports/mimxrt10xx/common-hal/busio/UART.h b/ports/mimxrt10xx/common-hal/busio/UART.h
index 604fef2cf3..78c91173a3 100644
--- a/ports/mimxrt10xx/common-hal/busio/UART.h
+++ b/ports/mimxrt10xx/common-hal/busio/UART.h
@@ -51,4 +51,5 @@ typedef struct {
     const mcu_periph_obj_t *rts;
 } busio_uart_obj_t;
 
+void uart_reset(void);
 #endif // MICROPY_INCLUDED_MIMXRT10XX_COMMON_HAL_BUSIO_UART_H
diff --git a/ports/mimxrt10xx/common-hal/digitalio/DigitalInOut.c b/ports/mimxrt10xx/common-hal/digitalio/DigitalInOut.c
index 445ffa91c5..27753f47dc 100644
--- a/ports/mimxrt10xx/common-hal/digitalio/DigitalInOut.c
+++ b/ports/mimxrt10xx/common-hal/digitalio/DigitalInOut.c
@@ -40,7 +40,7 @@
 
 #define IOMUXC_SW_MUX_CTL_PAD_MUX_MODE_ALT5 5U
 
-void pin_config(const mcu_pin_obj_t *pin, bool open_drain, digitalio_pull_t pull) {
+STATIC void pin_config(const mcu_pin_obj_t *pin, bool open_drain, digitalio_pull_t pull) {
     IOMUXC_SetPinConfig(0, 0, 0, 0, pin->cfg_reg,
         IOMUXC_SW_PAD_CTL_PAD_HYS(1)
         | IOMUXC_SW_PAD_CTL_PAD_PUS((pull == PULL_UP) ? 2 : 0)
diff --git a/ports/mimxrt10xx/common-hal/microcontroller/Processor.c b/ports/mimxrt10xx/common-hal/microcontroller/Processor.c
index b097133d57..697d97ca43 100644
--- a/ports/mimxrt10xx/common-hal/microcontroller/Processor.c
+++ b/ports/mimxrt10xx/common-hal/microcontroller/Processor.c
@@ -28,6 +28,7 @@
 #include <math.h>
 
 #include "common-hal/microcontroller/Processor.h"
+#include "shared-bindings/microcontroller/Processor.h"
 #include "shared-bindings/microcontroller/ResetReason.h"
 
 #include "fsl_tempmon.h"
diff --git a/ports/mimxrt10xx/common-hal/os/__init__.c b/ports/mimxrt10xx/common-hal/os/__init__.c
index dd1d186f1c..e2c43e43fa 100644
--- a/ports/mimxrt10xx/common-hal/os/__init__.c
+++ b/ports/mimxrt10xx/common-hal/os/__init__.c
@@ -31,6 +31,8 @@
 #include "py/objtuple.h"
 #include "py/qstr.h"
 
+#include "shared-bindings/os/__init__.h"
+
 #include "fsl_trng.h"
 
 STATIC const qstr os_uname_info_fields[] = {
@@ -58,7 +60,7 @@ mp_obj_t common_hal_os_uname(void) {
     return (mp_obj_t)&os_uname_info_obj;
 }
 
-bool common_hal_os_urandom(uint8_t *buffer, uint32_t length) {
+bool common_hal_os_urandom(uint8_t *buffer, mp_uint_t length) {
     trng_config_t trngConfig;
 
     TRNG_GetDefaultConfig(&trngConfig);
diff --git a/ports/mimxrt10xx/common-hal/rtc/RTC.c b/ports/mimxrt10xx/common-hal/rtc/RTC.c
index 8619a7eaec..04aa799ce5 100644
--- a/ports/mimxrt10xx/common-hal/rtc/RTC.c
+++ b/ports/mimxrt10xx/common-hal/rtc/RTC.c
@@ -31,6 +31,8 @@
 #include "py/runtime.h"
 #include "shared/timeutils/timeutils.h"
 #include "shared-bindings/rtc/__init__.h"
+#include "shared-bindings/rtc/RTC.h"
+#include "common-hal/rtc/RTC.h"
 #include "supervisor/shared/translate.h"
 
 #include "fsl_snvs_hp.h"
diff --git a/ports/mimxrt10xx/mphalport.c b/ports/mimxrt10xx/mphalport.c
index ff7a880ab7..ad0fb4d9ba 100644
--- a/ports/mimxrt10xx/mphalport.c
+++ b/ports/mimxrt10xx/mphalport.c
@@ -25,6 +25,7 @@
  * THE SOFTWARE.
  */
 
+#include "py/mphal.h"
 #include "py/mpstate.h"
 #include "py/smallint.h"
 
diff --git a/ports/mimxrt10xx/peripherals/mimxrt10xx/MIMXRT1011/clocks.c b/ports/mimxrt10xx/peripherals/mimxrt10xx/MIMXRT1011/clocks.c
index e6354386a9..e96b55f3e9 100644
--- a/ports/mimxrt10xx/peripherals/mimxrt10xx/MIMXRT1011/clocks.c
+++ b/ports/mimxrt10xx/peripherals/mimxrt10xx/MIMXRT1011/clocks.c
@@ -35,6 +35,8 @@
 #include "fsl_clock.h"
 #include "fsl_iomuxc.h"
 
+#include "clocks.h"
+
 #define BOARD_XTAL0_CLK_HZ 24000000U /*!< Board xtal0 frequency in Hz */
 #define BOARD_XTAL32K_CLK_HZ 32768U /*!< Board xtal32k frequency in Hz */
 
diff --git a/ports/mimxrt10xx/supervisor/flexspi_nor_flash_ops.c b/ports/mimxrt10xx/supervisor/flexspi_nor_flash_ops.c
index 251e6f9acd..950e9aa403 100644
--- a/ports/mimxrt10xx/supervisor/flexspi_nor_flash_ops.c
+++ b/ports/mimxrt10xx/supervisor/flexspi_nor_flash_ops.c
@@ -10,9 +10,10 @@
 #include "fsl_flexspi.h"
 #include "internal_flash.h"
 #include "boards/flash_config.h"
+#include "supervisor/internal_flash.h"
 #include "supervisor/linker.h"
 
-status_t PLACE_IN_ITCM(flexspi_nor_write_enable)(FLEXSPI_Type * base, uint32_t baseAddr)
+STATIC status_t PLACE_IN_ITCM(flexspi_nor_write_enable)(FLEXSPI_Type * base, uint32_t baseAddr)
 {
     flexspi_transfer_t flashXfer;
     status_t status;
@@ -29,7 +30,7 @@ status_t PLACE_IN_ITCM(flexspi_nor_write_enable)(FLEXSPI_Type * base, uint32_t b
     return status;
 }
 
-status_t PLACE_IN_ITCM(flexspi_nor_wait_bus_busy)(FLEXSPI_Type * base)
+STATIC status_t PLACE_IN_ITCM(flexspi_nor_wait_bus_busy)(FLEXSPI_Type * base)
 {
     /* Wait status ready. */
     bool isBusy;
diff --git a/ports/mimxrt10xx/supervisor/internal_flash.c b/ports/mimxrt10xx/supervisor/internal_flash.c
index 84c478bcfb..72d57d1dd4 100644
--- a/ports/mimxrt10xx/supervisor/internal_flash.c
+++ b/ports/mimxrt10xx/supervisor/internal_flash.c
@@ -52,10 +52,6 @@ extern uint32_t __fatfs_flash_length[];
 uint8_t _flash_cache[SECTOR_SIZE] __attribute__((aligned(4)));
 uint32_t _flash_page_addr = NO_CACHE;
 
-extern status_t flexspi_nor_flash_erase_sector(FLEXSPI_Type *base, uint32_t address);
-extern status_t flexspi_nor_flash_page_program(FLEXSPI_Type *base, uint32_t dstAddr, const uint32_t *src);
-extern status_t flexspi_nor_enable_quad_mode(FLEXSPI_Type *base);
-
 void PLACE_IN_ITCM(supervisor_flash_init)(void) {
     // Update the LUT to make sure all entries are available.
     FLEXSPI_UpdateLUT(FLEXSPI, 0, (const uint32_t *)&qspiflash_config.memConfig.lookupTable, 64);
diff --git a/ports/mimxrt10xx/supervisor/internal_flash.h b/ports/mimxrt10xx/supervisor/internal_flash.h
index ae33fd134f..66d3f73db1 100644
--- a/ports/mimxrt10xx/supervisor/internal_flash.h
+++ b/ports/mimxrt10xx/supervisor/internal_flash.h
@@ -30,6 +30,7 @@
 #include <stdint.h>
 
 #include "py/mpconfig.h"
+#include "fsl_common.h"
 
 #define INTERNAL_FLASH_SYSTICK_MASK     (0x1ff) // 512ms
 #define INTERNAL_FLASH_IDLE_TICK(tick)  (((tick) & INTERNAL_FLASH_SYSTICK_MASK) == 2)
@@ -41,4 +42,9 @@
 #define ROM_INDEX_PAGEPROGRAM 9
 #define ROM_INDEX_READSTATUSREG 1
 
+extern status_t flexspi_nor_flash_erase_sector(FLEXSPI_Type *base, uint32_t address);
+extern status_t flexspi_nor_flash_page_program(FLEXSPI_Type *base, uint32_t dstAddr, const uint32_t *src);
+extern status_t flexspi_nor_enable_quad_mode(FLEXSPI_Type *base);
+
+
 #endif  // MICROPY_INCLUDED_MIMXRT10XX_INTERNAL_FLASH_H
diff --git a/ports/mimxrt10xx/supervisor/port.c b/ports/mimxrt10xx/supervisor/port.c
index 88a4ce5bb7..0b25bb6d2a 100644
--- a/ports/mimxrt10xx/supervisor/port.c
+++ b/ports/mimxrt10xx/supervisor/port.c
@@ -104,6 +104,7 @@ extern uint32_t _ld_itcm_flash_copy;
 extern void main(void);
 
 // This replaces the Reset_Handler in startup_*.S and SystemInit in system_*.c.
+void Reset_Handler(void);
 __attribute__((used, naked)) void Reset_Handler(void) {
     __disable_irq();
     SCB->VTOR = (uint32_t)&__isr_vector;
@@ -358,6 +359,8 @@ uint64_t port_get_raw_ticks(uint8_t *subticks) {
     return ticks / 32;
 }
 
+void SNVS_HP_WRAPPER_IRQHandler(void);
+__attribute__((used))
 void SNVS_HP_WRAPPER_IRQHandler(void) {
     if ((SNVS->HPSR & SNVS_HPSR_PI_MASK) != 0) {
         supervisor_tick();
@@ -415,6 +418,7 @@ void port_idle_until_interrupt(void) {
 /**
  * \brief Default interrupt handler for unused IRQs.
  */
+void MemManage_Handler(void);
 __attribute__((used)) void MemManage_Handler(void) {
     reset_into_safe_mode(MEM_MANAGE);
     while (true) {
@@ -425,6 +429,7 @@ __attribute__((used)) void MemManage_Handler(void) {
 /**
  * \brief Default interrupt handler for unused IRQs.
  */
+void BusFault_Handler(void);
 __attribute__((used)) void BusFault_Handler(void) {
     reset_into_safe_mode(MEM_MANAGE);
     while (true) {
@@ -435,6 +440,7 @@ __attribute__((used)) void BusFault_Handler(void) {
 /**
  * \brief Default interrupt handler for unused IRQs.
  */
+void UsageFault_Handler(void);
 __attribute__((used)) void UsageFault_Handler(void) {
     reset_into_safe_mode(MEM_MANAGE);
     while (true) {
@@ -445,6 +451,7 @@ __attribute__((used)) void UsageFault_Handler(void) {
 /**
  * \brief Default interrupt handler for unused IRQs.
  */
+void HardFault_Handler(void);
 __attribute__((used)) void HardFault_Handler(void) {
     reset_into_safe_mode(HARD_CRASH);
     while (true) {
diff --git a/ports/mimxrt10xx/supervisor/usb.c b/ports/mimxrt10xx/supervisor/usb.c
index 57f0387990..c00ff44acd 100644
--- a/ports/mimxrt10xx/supervisor/usb.c
+++ b/ports/mimxrt10xx/supervisor/usb.c
@@ -52,6 +52,7 @@ void init_usb_hardware(void) {
     usb_phy->TX = phytx;
 }
 
+void USB_OTG1_IRQHandler(void);
 void USB_OTG1_IRQHandler(void) {
     usb_irq_handler();
 }