diff --git a/ports/atmel-samd/boards/pewpew_m4/board.c b/ports/atmel-samd/boards/pewpew_m4/board.c
index 6ce97f7b3f..5e339d88cb 100644
--- a/ports/atmel-samd/boards/pewpew_m4/board.c
+++ b/ports/atmel-samd/boards/pewpew_m4/board.c
@@ -50,7 +50,7 @@ typedef struct {
 
 #define DELAY 0x80
 
-uint32_t lookupCfg(uint32_t key, uint32_t defl) {
+STATIC uint32_t lookupCfg(uint32_t key, uint32_t defl) {
     const uint32_t *ptr = UF2_BINFO->config_data;
     if (!ptr || (((uint32_t)ptr) & 3) || *ptr != CFG_MAGIC0) {
         // no config data!
diff --git a/ports/atmel-samd/common-hal/canio/Listener.c b/ports/atmel-samd/common-hal/canio/Listener.c
index e171ae5193..5cdfafe9c0 100644
--- a/ports/atmel-samd/common-hal/canio/Listener.c
+++ b/ports/atmel-samd/common-hal/canio/Listener.c
@@ -195,7 +195,7 @@ STATIC void install_extended_filter(CanMramXidfe *extended, int id1, int id2, in
 
 
 #define NO_ID (-1)
-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) {
     int fifo = self->fifo_idx;
 
     if (!nmatch) {
diff --git a/ports/espressif/boards/ai_thinker_esp32-c3s/board.c b/ports/espressif/boards/ai_thinker_esp32-c3s/board.c
index 83ef690007..820228ef98 100644
--- a/ports/espressif/boards/ai_thinker_esp32-c3s/board.c
+++ b/ports/espressif/boards/ai_thinker_esp32-c3s/board.c
@@ -52,6 +52,3 @@ bool board_requests_safe_mode(void) {
 
 void reset_board(void) {
 }
-
-void board_deinit(void) {
-}