diff --git a/ports/espressif/Makefile b/ports/espressif/Makefile
index 9a928b40f4..7a034c9d2a 100644
--- a/ports/espressif/Makefile
+++ b/ports/espressif/Makefile
@@ -150,7 +150,7 @@ endif
 # option to override compiler optimization level, set in boards/$(BOARD)/mpconfigboard.mk
 CFLAGS += $(OPTIMIZATION_FLAGS)
 
-CFLAGS += $(INC) -Werror -Wall -std=gnu11 -Wl,--gc-sections $(BASE_CFLAGS) $(C_DEFS) $(CFLAGS_MOD) $(COPT)
+CFLAGS += $(INC) -Werror -Wall -std=gnu11 -Wl,--gc-sections $(BASE_CFLAGS) $(C_DEFS) $(CFLAGS_MOD) $(COPT) -Werror=missing-prototypes
 
 ifeq ($(IDF_TARGET_ARCH),xtensa)
 CFLAGS += -mlongcalls
diff --git a/ports/espressif/background.c b/ports/espressif/background.c
index 80b60bebe3..37fe3d5be0 100644
--- a/ports/espressif/background.c
+++ b/ports/espressif/background.c
@@ -26,6 +26,7 @@
 
 #include "py/runtime.h"
 #include "supervisor/filesystem.h"
+#include "supervisor/port.h"
 #include "supervisor/shared/stack.h"
 
 #include "freertos/FreeRTOS.h"
diff --git a/ports/espressif/bindings/espidf/__init__.c b/ports/espressif/bindings/espidf/__init__.c
index 9076294d53..4f7da39540 100644
--- a/ports/espressif/bindings/espidf/__init__.c
+++ b/ports/espressif/bindings/espidf/__init__.c
@@ -82,15 +82,7 @@ STATIC mp_obj_t espidf_erase_nvs(void) {
 MP_DEFINE_CONST_FUN_OBJ_0(espidf_erase_nvs_obj, espidf_erase_nvs);
 
 
-//| class IDFError(OSError):
-//|     """Raised for certain generic ESP IDF errors."""
-//|     ...
-//|
-NORETURN void mp_raise_espidf_IDFError(void) {
-    nlr_raise(mp_obj_new_exception(&mp_type_espidf_IDFError));
-}
-
-void espidf_exception_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind) {
+STATIC void espidf_exception_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind) {
     mp_print_kind_t k = kind & ~PRINT_EXC_SUBCLASS;
     bool is_subclass = kind & PRINT_EXC_SUBCLASS;
     if (!is_subclass && (k == PRINT_EXC)) {
diff --git a/ports/espressif/cam.c b/ports/espressif/cam.c
index e435993c6d..146df43a41 100644
--- a/ports/espressif/cam.c
+++ b/ports/espressif/cam.c
@@ -69,7 +69,7 @@ typedef struct {
 
 static cam_obj_t *cam_obj = NULL;
 
-void IRAM_ATTR cam_isr(void *arg) {
+static void IRAM_ATTR cam_isr(void *arg) {
     cam_event_t cam_event = {0};
     BaseType_t HPTaskAwoken = pdFALSE;
     typeof(I2S0.int_st) int_st = I2S0.int_st;
@@ -85,7 +85,7 @@ void IRAM_ATTR cam_isr(void *arg) {
     }
 }
 
-void IRAM_ATTR cam_vsync_isr(void *arg) {
+static void IRAM_ATTR cam_vsync_isr(void *arg) {
     cam_event_t cam_event = {0};
     BaseType_t HPTaskAwoken = pdFALSE;
     /*!< filter */
@@ -392,7 +392,7 @@ void cam_give(uint8_t *buffer) {
     }
 }
 
-void cam_dma_config(const cam_config_t *config) {
+static void cam_dma_config(const cam_config_t *config) {
     int cnt = 0;
 
     if (config->mode.jpeg) {
diff --git a/ports/espressif/common-hal/alarm/SleepMemory.c b/ports/espressif/common-hal/alarm/SleepMemory.c
index b25bf28d25..764125ddb2 100644
--- a/ports/espressif/common-hal/alarm/SleepMemory.c
+++ b/ports/espressif/common-hal/alarm/SleepMemory.c
@@ -29,6 +29,7 @@
 
 #include "py/runtime.h"
 #include "common-hal/alarm/SleepMemory.h"
+#include "shared-bindings/alarm/SleepMemory.h"
 
 #include "esp_log.h"
 #include "esp_sleep.h"
diff --git a/ports/espressif/common-hal/alarm/pin/PinAlarm.c b/ports/espressif/common-hal/alarm/pin/PinAlarm.c
index 970094783e..754902f678 100644
--- a/ports/espressif/common-hal/alarm/pin/PinAlarm.c
+++ b/ports/espressif/common-hal/alarm/pin/PinAlarm.c
@@ -72,7 +72,7 @@ gpio_isr_handle_t gpio_interrupt_handle;
 // Low and high are relative to pin number. 32+ is high. <32 is low.
 static volatile uint32_t pin_31_0_status = 0;
 static volatile uint32_t pin_63_32_status = 0;
-void gpio_interrupt(void *arg) {
+STATIC void gpio_interrupt(void *arg) {
     (void)arg;
 
     gpio_ll_get_intr_status(&GPIO, xPortGetCoreID(), (uint32_t *)&pin_31_0_status);
diff --git a/ports/espressif/common-hal/alarm/time/TimeAlarm.c b/ports/espressif/common-hal/alarm/time/TimeAlarm.c
index 0fb29a3ed4..256d96a75f 100644
--- a/ports/espressif/common-hal/alarm/time/TimeAlarm.c
+++ b/ports/espressif/common-hal/alarm/time/TimeAlarm.c
@@ -63,7 +63,7 @@ esp_timer_handle_t pretend_sleep_timer;
 STATIC bool woke_up = false;
 
 // This is run in the timer task. We use it to wake the main CircuitPython task.
-void timer_callback(void *arg) {
+STATIC void timer_callback(void *arg) {
     (void)arg;
     woke_up = true;
     xTaskNotifyGive(circuitpython_task);
diff --git a/ports/espressif/common-hal/alarm/touch/TouchAlarm.c b/ports/espressif/common-hal/alarm/touch/TouchAlarm.c
index e005999ee5..6ae2421e4c 100644
--- a/ports/espressif/common-hal/alarm/touch/TouchAlarm.c
+++ b/ports/espressif/common-hal/alarm/touch/TouchAlarm.c
@@ -75,7 +75,7 @@ mp_obj_t alarm_touch_touchalarm_create_wakeup_alarm(void) {
 }
 
 // This is used to wake the main CircuitPython task.
-void touch_interrupt(void *arg) {
+STATIC void touch_interrupt(void *arg) {
     (void)arg;
     woke_up = true;
     BaseType_t task_wakeup;
diff --git a/ports/espressif/common-hal/analogio/AnalogIn.c b/ports/espressif/common-hal/analogio/AnalogIn.c
index add4c3e14e..df39b30c63 100644
--- a/ports/espressif/common-hal/analogio/AnalogIn.c
+++ b/ports/espressif/common-hal/analogio/AnalogIn.c
@@ -25,6 +25,7 @@
  */
 
 #include "common-hal/analogio/AnalogIn.h"
+#include "shared-bindings/analogio/AnalogIn.h"
 #include "py/mperrno.h"
 #include "py/runtime.h"
 #include "supervisor/shared/translate.h"
diff --git a/ports/espressif/common-hal/canio/CAN.c b/ports/espressif/common-hal/canio/CAN.c
index 720034755b..eebf064f44 100644
--- a/ports/espressif/common-hal/canio/CAN.c
+++ b/ports/espressif/common-hal/canio/CAN.c
@@ -38,7 +38,7 @@
 
 STATIC bool reserved_can;
 
-twai_timing_config_t get_t_config(int baudrate) {
+STATIC twai_timing_config_t get_t_config(int baudrate) {
     switch (baudrate) {
         case 1000000: {
             // TWAI_TIMING_CONFIG_abc expands to a C designated initializer list
@@ -204,7 +204,7 @@ static void can_restart(void) {
     } while (port_get_raw_ticks(NULL) < deadline && (info.state == TWAI_STATE_BUS_OFF || info.state == TWAI_STATE_RECOVERING));
 }
 
-void canio_maybe_auto_restart(canio_can_obj_t *self) {
+STATIC void canio_maybe_auto_restart(canio_can_obj_t *self) {
     if (self->auto_restart) {
         can_restart();
     }
diff --git a/ports/espressif/common-hal/canio/Listener.c b/ports/espressif/common-hal/canio/Listener.c
index 8100261743..eccddf6243 100644
--- a/ports/espressif/common-hal/canio/Listener.c
+++ b/ports/espressif/common-hal/canio/Listener.c
@@ -78,7 +78,7 @@ STATIC void install_all_match_filter(canio_listener_obj_t *self) {
 }
 
 __attribute__((noinline,optimize("O0")))
-void set_filters(canio_listener_obj_t *self, size_t nmatch, canio_match_obj_t **matches) {
+STATIC void set_filters(canio_listener_obj_t *self, size_t nmatch, canio_match_obj_t **matches) {
     twai_ll_enter_reset_mode(&TWAI);
 
     if (!nmatch) {
diff --git a/ports/espressif/common-hal/countio/Counter.c b/ports/espressif/common-hal/countio/Counter.c
index bdc8b290fe..418a8ae4d4 100644
--- a/ports/espressif/common-hal/countio/Counter.c
+++ b/ports/espressif/common-hal/countio/Counter.c
@@ -25,6 +25,7 @@
  */
 
 #include "common-hal/countio/Counter.h"
+#include "shared-bindings/countio/Counter.h"
 #include "common-hal/microcontroller/Pin.h"
 
 #include "py/runtime.h"
diff --git a/ports/espressif/common-hal/microcontroller/Processor.c b/ports/espressif/common-hal/microcontroller/Processor.c
index 5f956b4412..c50c6fbf7a 100644
--- a/ports/espressif/common-hal/microcontroller/Processor.c
+++ b/ports/espressif/common-hal/microcontroller/Processor.c
@@ -31,6 +31,7 @@
 #include "py/runtime.h"
 
 #include "common-hal/microcontroller/Processor.h"
+#include "shared-bindings/microcontroller/Processor.h"
 #include "shared-bindings/microcontroller/ResetReason.h"
 #include "supervisor/shared/translate.h"
 
diff --git a/ports/espressif/common-hal/nvm/ByteArray.c b/ports/espressif/common-hal/nvm/ByteArray.c
index 6eeed72e2e..a17e368249 100644
--- a/ports/espressif/common-hal/nvm/ByteArray.c
+++ b/ports/espressif/common-hal/nvm/ByteArray.c
@@ -27,13 +27,14 @@
 #include <string.h>
 
 #include "common-hal/nvm/ByteArray.h"
+#include "shared-bindings/nvm/ByteArray.h"
 #include "bindings/espidf/__init__.h"
 
 #include "py/runtime.h"
 #include "py/gc.h"
 #include "nvs_flash.h"
 
-uint32_t common_hal_nvm_bytearray_get_length(nvm_bytearray_obj_t *self) {
+uint32_t common_hal_nvm_bytearray_get_length(const nvm_bytearray_obj_t *self) {
     return self->len;
 }
 
@@ -75,7 +76,7 @@ static esp_err_t get_bytes(nvs_handle_t handle, uint8_t **buf_out) {
     return result;
 }
 
-bool common_hal_nvm_bytearray_set_bytes(nvm_bytearray_obj_t *self,
+bool common_hal_nvm_bytearray_set_bytes(const nvm_bytearray_obj_t *self,
     uint32_t start_index, uint8_t *values, uint32_t len) {
 
     // start nvs
@@ -122,7 +123,7 @@ bool common_hal_nvm_bytearray_set_bytes(nvm_bytearray_obj_t *self,
     return true;
 }
 
-void common_hal_nvm_bytearray_get_bytes(nvm_bytearray_obj_t *self,
+void common_hal_nvm_bytearray_get_bytes(const nvm_bytearray_obj_t *self,
     uint32_t start_index, uint32_t len, uint8_t *values) {
 
     // start nvs
diff --git a/ports/espressif/common-hal/os/__init__.c b/ports/espressif/common-hal/os/__init__.c
index b77898016f..1dcd3e46e0 100644
--- a/ports/espressif/common-hal/os/__init__.c
+++ b/ports/espressif/common-hal/os/__init__.c
@@ -30,6 +30,8 @@
 #include "py/objtuple.h"
 #include "py/qstr.h"
 
+#include "shared-bindings/os/__init__.h"
+
 #include "esp_system.h"
 
 STATIC const qstr os_uname_info_fields[] = {
diff --git a/ports/espressif/common-hal/ps2io/Ps2.c b/ports/espressif/common-hal/ps2io/Ps2.c
index f4845b0fa8..2b6dc52967 100644
--- a/ports/espressif/common-hal/ps2io/Ps2.c
+++ b/ports/espressif/common-hal/ps2io/Ps2.c
@@ -25,6 +25,7 @@
  */
 
 #include "common-hal/ps2io/Ps2.h"
+#include "shared-bindings/ps2io/Ps2.h"
 
 #include "supervisor/port.h"
 #include "shared-bindings/microcontroller/__init__.h"
diff --git a/ports/espressif/common-hal/pulseio/PulseIn.c b/ports/espressif/common-hal/pulseio/PulseIn.c
index 4b314e2f8d..3f5457f84b 100644
--- a/ports/espressif/common-hal/pulseio/PulseIn.c
+++ b/ports/espressif/common-hal/pulseio/PulseIn.c
@@ -25,6 +25,7 @@
  */
 
 #include "common-hal/pulseio/PulseIn.h"
+#include "shared-bindings/pulseio/PulseIn.h"
 #include "shared-bindings/microcontroller/__init__.h"
 #include "py/runtime.h"
 
diff --git a/ports/espressif/common-hal/pulseio/PulseOut.c b/ports/espressif/common-hal/pulseio/PulseOut.c
index 1cb02089e7..993fd9452c 100644
--- a/ports/espressif/common-hal/pulseio/PulseOut.c
+++ b/ports/espressif/common-hal/pulseio/PulseOut.c
@@ -25,6 +25,7 @@
  */
 
 #include "common-hal/pulseio/PulseOut.h"
+#include "shared-bindings/pulseio/PulseOut.h"
 
 #include "shared-bindings/pwmio/PWMOut.h"
 #include "py/runtime.h"
diff --git a/ports/espressif/common-hal/rotaryio/IncrementalEncoder.c b/ports/espressif/common-hal/rotaryio/IncrementalEncoder.c
index b36c79b4f6..676e99289d 100644
--- a/ports/espressif/common-hal/rotaryio/IncrementalEncoder.c
+++ b/ports/espressif/common-hal/rotaryio/IncrementalEncoder.c
@@ -25,6 +25,7 @@
  */
 
 #include "common-hal/rotaryio/IncrementalEncoder.h"
+#include "shared-bindings/rotaryio/IncrementalEncoder.h"
 #include "common-hal/microcontroller/Pin.h"
 
 #include "py/runtime.h"
diff --git a/ports/espressif/common-hal/ssl/__init__.c b/ports/espressif/common-hal/ssl/__init__.c
index a0886adda7..61ea32f395 100644
--- a/ports/espressif/common-hal/ssl/__init__.c
+++ b/ports/espressif/common-hal/ssl/__init__.c
@@ -24,6 +24,7 @@
  * THE SOFTWARE.
  */
 
+#include "shared-bindings/ssl/__init__.h"
 #include "shared-bindings/ssl/SSLContext.h"
 
 #include "components/mbedtls/esp_crt_bundle/include/esp_crt_bundle.h"
diff --git a/ports/espressif/common-hal/watchdog/WatchDogTimer.c b/ports/espressif/common-hal/watchdog/WatchDogTimer.c
index 729ab5815a..159c99458f 100644
--- a/ports/espressif/common-hal/watchdog/WatchDogTimer.c
+++ b/ports/espressif/common-hal/watchdog/WatchDogTimer.c
@@ -32,6 +32,7 @@
 
 #include "esp_task_wdt.h"
 
+extern void esp_task_wdt_isr_user_handler(void);
 void esp_task_wdt_isr_user_handler(void) {
     mp_obj_exception_clear_traceback(MP_OBJ_FROM_PTR(&mp_watchdog_timeout_exception));
     MP_STATE_THREAD(mp_pending_exception) = &mp_watchdog_timeout_exception;
diff --git a/ports/espressif/common-hal/wifi/__init__.c b/ports/espressif/common-hal/wifi/__init__.c
index 8d19a91cb2..a39103ce0a 100644
--- a/ports/espressif/common-hal/wifi/__init__.c
+++ b/ports/espressif/common-hal/wifi/__init__.c
@@ -25,6 +25,7 @@
  */
 
 #include "common-hal/wifi/__init__.h"
+#include "shared-bindings/wifi/__init__.h"
 
 #include "shared-bindings/ipaddress/IPv4Address.h"
 #include "shared-bindings/wifi/Radio.h"
diff --git a/ports/espressif/mphalport.c b/ports/espressif/mphalport.c
index 632e18039a..f22856f0a4 100644
--- a/ports/espressif/mphalport.c
+++ b/ports/espressif/mphalport.c
@@ -39,6 +39,8 @@
 #include "components/esp_rom/include/esp32s2/rom/ets_sys.h"
 #endif
 
+#include "supervisor/cpu.h"
+
 void mp_hal_delay_us(mp_uint_t delay) {
     ets_delay_us(delay);
 }
@@ -48,7 +50,7 @@ void mp_hal_delay_us(mp_uint_t delay) {
 extern void xthal_window_spill(void);
 #endif
 
-mp_uint_t cpu_get_regs_and_sp(mp_uint_t *regs, uint8_t reg_count) {
+mp_uint_t cpu_get_regs_and_sp(mp_uint_t *regs) {
     // xtensa has more registers than an instruction can address. The 16 that
     // can be addressed are called the "window". When a function is called or
     // returns the window rotates. This allows for more efficient function calls
diff --git a/ports/espressif/supervisor/internal_flash.c b/ports/espressif/supervisor/internal_flash.c
index 8f3d917765..2f17b48f0c 100644
--- a/ports/espressif/supervisor/internal_flash.c
+++ b/ports/espressif/supervisor/internal_flash.c
@@ -39,6 +39,7 @@
 
 #include "components/spi_flash/include/esp_partition.h"
 
+#include "supervisor/flash.h"
 #include "supervisor/usb.h"
 
 STATIC const esp_partition_t *_partition;
diff --git a/ports/espressif/supervisor/port.c b/ports/espressif/supervisor/port.c
index 7425bb615e..30106075e7 100644
--- a/ports/espressif/supervisor/port.c
+++ b/ports/espressif/supervisor/port.c
@@ -93,7 +93,7 @@ TaskHandle_t circuitpython_task = NULL;
 
 extern void esp_restart(void) NORETURN;
 
-void tick_timer_cb(void *arg) {
+STATIC void tick_timer_cb(void *arg) {
     supervisor_tick();
 
     // CircuitPython's VM is run in a separate FreeRTOS task from timer callbacks. So, we have to
@@ -360,6 +360,7 @@ void port_idle_until_interrupt(void) {
 
 // Wrap main in app_main that the IDF expects.
 extern void main(void);
+extern void app_main(void);
 void app_main(void) {
     main();
 }
diff --git a/ports/espressif/supervisor/usb.c b/ports/espressif/supervisor/usb.c
index fa9d09fa44..2137a7b0a4 100644
--- a/ports/espressif/supervisor/usb.c
+++ b/ports/espressif/supervisor/usb.c
@@ -62,7 +62,7 @@ StaticTask_t usb_device_taskdef;
 
 // USB Device Driver task
 // This top level thread process all usb events and invoke callbacks
-void usb_device_task(void *param) {
+STATIC void usb_device_task(void *param) {
     (void)param;
 
     // RTOS forever loop
diff --git a/shared-module/canio/Match.c b/shared-module/canio/Match.c
index b4e8616e9b..ae8fd40893 100644
--- a/shared-module/canio/Match.c
+++ b/shared-module/canio/Match.c
@@ -25,6 +25,7 @@
  */
 
 #include "shared-module/canio/Match.h"
+#include "shared-bindings/canio/Match.h"
 
 void common_hal_canio_match_construct(canio_match_obj_t *self, int id, int mask, bool extended) {
     self->id = id;
diff --git a/shared-module/canio/Message.c b/shared-module/canio/Message.c
index 08e4d9fda7..7c0dcf739a 100644
--- a/shared-module/canio/Message.c
+++ b/shared-module/canio/Message.c
@@ -25,6 +25,7 @@
  */
 
 #include "shared-module/canio/Message.h"
+#include "shared-bindings/canio/Message.h"
 
 #include <string.h>