diff --git a/ports/atmel-samd/audio_dma.c b/ports/atmel-samd/audio_dma.c
index 4dbb0a0006..3d5cbf6790 100644
--- a/ports/atmel-samd/audio_dma.c
+++ b/ports/atmel-samd/audio_dma.c
@@ -432,4 +432,6 @@ void audio_dma_evsys_handler(void) {
     }
 }
 
+MP_REGISTER_ROOT_POINTER(mp_obj_t playing_audio[AUDIO_DMA_CHANNEL_COUNT]);
+
 #endif
diff --git a/ports/atmel-samd/mpconfigport.h b/ports/atmel-samd/mpconfigport.h
index 6fb969e47b..19e95f1e96 100644
--- a/ports/atmel-samd/mpconfigport.h
+++ b/ports/atmel-samd/mpconfigport.h
@@ -270,13 +270,4 @@
 
 #include "peripherals/samd/dma.h"
 
-#if CIRCUITPY_AUDIOCORE
-#define MICROPY_PORT_ROOT_POINTERS \
-    CIRCUITPY_COMMON_ROOT_POINTERS \
-    mp_obj_t playing_audio[AUDIO_DMA_CHANNEL_COUNT];
-#else
-#define MICROPY_PORT_ROOT_POINTERS \
-    CIRCUITPY_COMMON_ROOT_POINTERS
-#endif
-
 #endif  // __INCLUDED_MPCONFIGPORT_H
diff --git a/ports/broadcom/mpconfigport.h b/ports/broadcom/mpconfigport.h
index e77725cca3..6b73edaee8 100644
--- a/ports/broadcom/mpconfigport.h
+++ b/ports/broadcom/mpconfigport.h
@@ -57,7 +57,4 @@
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-#define MICROPY_PORT_ROOT_POINTERS \
-    CIRCUITPY_COMMON_ROOT_POINTERS
-
 #endif  // __INCLUDED_MPCONFIGPORT_H
diff --git a/ports/cxd56/mpconfigport.h b/ports/cxd56/mpconfigport.h
index 3560e72855..a0f5c0c1e1 100644
--- a/ports/cxd56/mpconfigport.h
+++ b/ports/cxd56/mpconfigport.h
@@ -45,7 +45,4 @@
 
 #define MICROPY_BYTES_PER_GC_BLOCK              (32)
 
-#define MICROPY_PORT_ROOT_POINTERS \
-    CIRCUITPY_COMMON_ROOT_POINTERS \
-
 #endif  // __INCLUDED_MPCONFIGPORT_H
diff --git a/ports/espressif/bindings/espnow/ESPNow.c b/ports/espressif/bindings/espnow/ESPNow.c
index 211cb080d4..1f544758d1 100644
--- a/ports/espressif/bindings/espnow/ESPNow.c
+++ b/ports/espressif/bindings/espnow/ESPNow.c
@@ -368,3 +368,5 @@ MP_DEFINE_CONST_OBJ_TYPE(
     protocol, &espnow_stream_p,
     unary_op, &espnow_unary_op
     );
+
+MP_REGISTER_ROOT_POINTER(struct _espnow_obj_t *espnow_singleton);
diff --git a/ports/espressif/common-hal/_bleio/ble_events.c b/ports/espressif/common-hal/_bleio/ble_events.c
index a072a80623..e5c4608cd7 100644
--- a/ports/espressif/common-hal/_bleio/ble_events.c
+++ b/ports/espressif/common-hal/_bleio/ble_events.c
@@ -126,3 +126,5 @@ int ble_event_run_handlers(struct ble_gap_event *event) {
     #endif
     return 0;
 }
+
+MP_REGISTER_ROOT_POINTER(struct ble_event_handler_entry *ble_event_handler_entries);
diff --git a/ports/espressif/mpconfigport.h b/ports/espressif/mpconfigport.h
index e4733356bb..481a2f4517 100644
--- a/ports/espressif/mpconfigport.h
+++ b/ports/espressif/mpconfigport.h
@@ -37,23 +37,6 @@
 
 #include "py/circuitpy_mpconfig.h"
 
-#if CIRCUITPY_BLEIO
-#define BLEIO_ROOT_POINTERS struct ble_event_handler_entry *ble_event_handler_entries;
-#else
-#define BLEIO_ROOT_POINTERS
-#endif
-
-#if CIRCUITPY_ESPNOW
-#define ESPNOW_ROOT_POINTERS struct _espnow_obj_t *espnow_singleton;
-#else
-#define ESPNOW_ROOT_POINTERS
-#endif
-
-#define MICROPY_PORT_ROOT_POINTERS  \
-    CIRCUITPY_COMMON_ROOT_POINTERS  \
-    BLEIO_ROOT_POINTERS             \
-    ESPNOW_ROOT_POINTERS
-
 #define MICROPY_NLR_SETJMP                  (1)
 #define CIRCUITPY_DEFAULT_STACK_SIZE        0x6000
 
diff --git a/ports/litex/mpconfigport.h b/ports/litex/mpconfigport.h
index cedc3badc3..9b214c5799 100644
--- a/ports/litex/mpconfigport.h
+++ b/ports/litex/mpconfigport.h
@@ -34,8 +34,6 @@
 
 #include "py/circuitpy_mpconfig.h"
 
-#define MICROPY_PORT_ROOT_POINTERS \
-    CIRCUITPY_COMMON_ROOT_POINTERS
 #define MICROPY_NLR_SETJMP                  (1)
 #define CIRCUITPY_DEFAULT_STACK_SIZE        0x6000
 
diff --git a/ports/mimxrt10xx/mpconfigport.h b/ports/mimxrt10xx/mpconfigport.h
index 7cc17494bf..eedfaaec15 100644
--- a/ports/mimxrt10xx/mpconfigport.h
+++ b/ports/mimxrt10xx/mpconfigport.h
@@ -52,10 +52,7 @@ extern uint8_t _ld_default_stack_size;
 
 #include "py/circuitpy_mpconfig.h"
 
-#define MICROPY_PORT_ROOT_POINTERS \
-    CIRCUITPY_COMMON_ROOT_POINTERS \
-
 // TODO:
-//    mp_obj_t playing_audio[AUDIO_DMA_CHANNEL_COUNT];
+//    mp_obj_t playing_audio[AUDIO_DMA_CHANNEL_COUNT] as an MP_REGISTER_ROOT_POINTER.
 
 #endif  // __INCLUDED_MPCONFIGPORT_H
diff --git a/ports/nrf/bluetooth/ble_drv.c b/ports/nrf/bluetooth/ble_drv.c
index e3914e6a18..48c40d7082 100644
--- a/ports/nrf/bluetooth/ble_drv.c
+++ b/ports/nrf/bluetooth/ble_drv.c
@@ -196,3 +196,5 @@ void SD_EVT_IRQHandler(void) {
     ble_serial_enable();
     #endif
 }
+
+MP_REGISTER_ROOT_POINTER(ble_drv_evt_handler_entry_t *ble_drv_evt_handler_entries);
diff --git a/ports/nrf/common-hal/neopixel_write/__init__.c b/ports/nrf/common-hal/neopixel_write/__init__.c
index ce8ee8c7cf..f5f6335e5e 100644
--- a/ports/nrf/common-hal/neopixel_write/__init__.c
+++ b/ports/nrf/common-hal/neopixel_write/__init__.c
@@ -333,3 +333,5 @@ void common_hal_neopixel_write(const digitalio_digitalinout_obj_t *digitalinout,
     // Update the next start.
     next_start_raw_ticks = port_get_raw_ticks(NULL) + 4;
 }
+
+MP_REGISTER_ROOT_POINTER(uint16_t *pixels_pattern_heap);
diff --git a/ports/nrf/mpconfigport.h b/ports/nrf/mpconfigport.h
index 4726d51c55..d97d9277d0 100644
--- a/ports/nrf/mpconfigport.h
+++ b/ports/nrf/mpconfigport.h
@@ -204,11 +204,4 @@
 #error RAM size regions do not use all of RAM
 #endif
 
-
-#define MICROPY_PORT_ROOT_POINTERS                              \
-    CIRCUITPY_COMMON_ROOT_POINTERS                              \
-    uint16_t *pixels_pattern_heap;                              \
-    ble_drv_evt_handler_entry_t *ble_drv_evt_handler_entries;   \
-
-
 #endif  // NRF5_MPCONFIGPORT_H__
diff --git a/ports/raspberrypi/audio_dma.c b/ports/raspberrypi/audio_dma.c
index b5bd8c069c..8ea58acc3c 100644
--- a/ports/raspberrypi/audio_dma.c
+++ b/ports/raspberrypi/audio_dma.c
@@ -487,4 +487,5 @@ void isr_dma_0(void) {
     }
 }
 
+MP_REGISTER_ROOT_POINTER(mp_obj_t playing_audio[NUM_DMA_CHANNELS]);
 #endif
diff --git a/ports/raspberrypi/common-hal/countio/Counter.c b/ports/raspberrypi/common-hal/countio/Counter.c
index e360b6f06b..a6c98f113f 100644
--- a/ports/raspberrypi/common-hal/countio/Counter.c
+++ b/ports/raspberrypi/common-hal/countio/Counter.c
@@ -111,3 +111,5 @@ void counter_interrupt_handler(void) {
         self->count += 65536;
     }
 }
+
+MP_REGISTER_ROOT_POINTER(mp_obj_t counting[NUM_PWM_SLICES]);
diff --git a/ports/raspberrypi/common-hal/rp2pio/StateMachine.c b/ports/raspberrypi/common-hal/rp2pio/StateMachine.c
index 629811ab9f..573996a269 100644
--- a/ports/raspberrypi/common-hal/rp2pio/StateMachine.c
+++ b/ports/raspberrypi/common-hal/rp2pio/StateMachine.c
@@ -1098,3 +1098,5 @@ bool common_hal_rp2pio_statemachine_get_writing(rp2pio_statemachine_obj_t *self)
 int common_hal_rp2pio_statemachine_get_pending(rp2pio_statemachine_obj_t *self) {
     return self->pending_buffers;
 }
+
+MP_REGISTER_ROOT_POINTER(mp_obj_t background_pio[NUM_DMA_CHANNELS]);
diff --git a/ports/raspberrypi/mpconfigport.h b/ports/raspberrypi/mpconfigport.h
index 4458107974..0c5f2d3402 100644
--- a/ports/raspberrypi/mpconfigport.h
+++ b/ports/raspberrypi/mpconfigport.h
@@ -55,12 +55,6 @@
 // This also includes mpconfigboard.h.
 #include "py/circuitpy_mpconfig.h"
 
-#define MICROPY_PORT_ROOT_POINTERS \
-    mp_obj_t counting[NUM_PWM_SLICES]; \
-    mp_obj_t playing_audio[NUM_DMA_CHANNELS]; \
-    mp_obj_t background_pio[NUM_DMA_CHANNELS]; \
-    CIRCUITPY_COMMON_ROOT_POINTERS;
-
 #if CIRCUITPY_CYW43
 #include "pico/cyw43_arch.h"
 #define MICROPY_PY_LWIP_ENTER   cyw43_arch_lwip_begin();
diff --git a/ports/silabs/mpconfigport.h b/ports/silabs/mpconfigport.h
index ba498dd763..ce7739ccca 100644
--- a/ports/silabs/mpconfigport.h
+++ b/ports/silabs/mpconfigport.h
@@ -65,9 +65,4 @@
 
 #include "py/circuitpy_mpconfig.h"
 
-#define MICROPY_PORT_ROOT_POINTERS    \
-    void *cpy_uart_obj_all[MAX_UART]; \
-    void *cpy_i2c_obj_all[MAX_I2C];   \
-    CIRCUITPY_COMMON_ROOT_POINTERS
-
 #endif  // EFR32_MPCONFIGPORT_H__
diff --git a/ports/stm/common-hal/busio/I2C.c b/ports/stm/common-hal/busio/I2C.c
index b78aff8e4f..7c3a0d59ad 100644
--- a/ports/stm/common-hal/busio/I2C.c
+++ b/ports/stm/common-hal/busio/I2C.c
@@ -400,3 +400,5 @@ void I2C3_EV_IRQHandler(void) {
 void I2C4_EV_IRQHandler(void) {
     call_hal_irq(4);
 }
+
+MP_REGISTER_ROOT_POINTER(void *cpy_i2c_obj_all[MAX_I2C]);
diff --git a/ports/stm/common-hal/busio/UART.c b/ports/stm/common-hal/busio/UART.c
index 59e98409c7..7635c4aaf3 100644
--- a/ports/stm/common-hal/busio/UART.c
+++ b/ports/stm/common-hal/busio/UART.c
@@ -674,3 +674,5 @@ STATIC void uart_assign_irq(busio_uart_obj_t *self, USART_TypeDef *USARTx) {
     }
     #endif
 }
+
+MP_REGISTER_ROOT_POINTER(void *cpy_uart_obj_all[MAX_UART]);
diff --git a/ports/stm/mpconfigport.h b/ports/stm/mpconfigport.h
index 94fccd53e9..fc1f4ae336 100644
--- a/ports/stm/mpconfigport.h
+++ b/ports/stm/mpconfigport.h
@@ -60,9 +60,4 @@ extern uint8_t _ld_default_stack_size;
 #define MAX_I2C 4
 #define MAX_SPI 6
 
-#define MICROPY_PORT_ROOT_POINTERS \
-    void *cpy_uart_obj_all[MAX_UART]; \
-    void *cpy_i2c_obj_all[MAX_I2C]; \
-    CIRCUITPY_COMMON_ROOT_POINTERS
-
 #endif  // __INCLUDED_MPCONFIGPORT_H
diff --git a/py/mpconfig.h b/py/mpconfig.h
index 0ce5d50b57..ca205a6e8c 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -1769,11 +1769,6 @@ typedef double mp_float_t;
 #define MICROPY_PORT_CONSTANTS
 #endif
 
-// Any root pointers for GC scanning - see mpstate.c
-#ifndef MICROPY_PORT_ROOT_POINTERS
-#define MICROPY_PORT_ROOT_POINTERS
-#endif
-
 /*****************************************************************************/
 /* Hooks for a port to wrap functions with attributes                        */
 
diff --git a/shared-bindings/displayio/Group.c b/shared-bindings/displayio/Group.c
index de07916bba..03ba3c4165 100644
--- a/shared-bindings/displayio/Group.c
+++ b/shared-bindings/displayio/Group.c
@@ -352,7 +352,7 @@ MP_DEFINE_CONST_OBJ_TYPE(
     displayio_group_type,
     MP_QSTR_Group,
     MP_TYPE_FLAG_ITER_IS_GETITER,
-    .make_new, displayio_group_make_new,
+    make_new, displayio_group_make_new,
     locals_dict, &displayio_group_locals_dict,
     subscr, group_subscr,
     unary_op, group_unary_op,
diff --git a/shared-bindings/displayio/Palette.c b/shared-bindings/displayio/Palette.c
index 7c36a2d46b..dcf0f7bd9b 100644
--- a/shared-bindings/displayio/Palette.c
+++ b/shared-bindings/displayio/Palette.c
@@ -141,7 +141,7 @@ STATIC mp_obj_t palette_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t val
     // Convert a tuple or list to a bytearray.
     if (mp_obj_is_type(value, &mp_type_tuple) ||
         mp_obj_is_type(value, &mp_type_list)) {
-        value = mp_type_bytes.make_new(&mp_type_bytes, 1, 0, &value);
+        value = MP_OBJ_TYPE_GET_SLOT(&mp_type_bytes, make_new)(&mp_type_bytes, 1, 0, &value);
     }
 
     uint32_t color;
diff --git a/shared-bindings/pulseio/PulseOut.c b/shared-bindings/pulseio/PulseOut.c
index 13188c0d14..8d130d2a70 100644
--- a/shared-bindings/pulseio/PulseOut.c
+++ b/shared-bindings/pulseio/PulseOut.c
@@ -148,6 +148,7 @@ STATIC const mp_rom_map_elem_t pulseio_pulseout_locals_dict_table[] = {
 STATIC MP_DEFINE_CONST_DICT(pulseio_pulseout_locals_dict, pulseio_pulseout_locals_dict_table);
 
 MP_DEFINE_CONST_OBJ_TYPE(
+    pulseio_pulseout_type,
     MP_QSTR_PulseOut,
     MP_TYPE_FLAG_NONE,
     make_new, pulseio_pulseout_make_new,
diff --git a/shared-bindings/terminalio/Terminal.c b/shared-bindings/terminalio/Terminal.c
index 50f4264b24..27544059eb 100644
--- a/shared-bindings/terminalio/Terminal.c
+++ b/shared-bindings/terminalio/Terminal.c
@@ -145,7 +145,6 @@ MP_DEFINE_CONST_OBJ_TYPE(
     MP_TYPE_FLAG_ITER_IS_ITERNEXT,
     make_new, terminalio_terminal_make_new,
     locals_dict, (mp_obj_dict_t *)&terminalio_terminal_locals_dict,
-    getiter, mp_identity_getiter,
-    iternext, mp_stream_unbuffered_iter,
+    iter, mp_stream_unbuffered_iter,
     protocol, &terminalio_terminal_stream_p
     );
diff --git a/supervisor/shared/external_flash/external_flash.c b/supervisor/shared/external_flash/external_flash.c
index 5b1e0b1793..79c6a6987f 100644
--- a/supervisor/shared/external_flash/external_flash.c
+++ b/supervisor/shared/external_flash/external_flash.c
@@ -33,6 +33,7 @@
 #include "supervisor/shared/external_flash/common_commands.h"
 #include "extmod/vfs.h"
 #include "extmod/vfs_fat.h"
+#include "py/gc.h"
 #include "py/misc.h"
 #include "py/obj.h"
 #include "py/runtime.h"
@@ -367,7 +368,8 @@ static bool allocate_ram_cache(void) {
         return true;
     }
 
-    if (MP_STATE_MEM(gc_pool_start) == 0) {
+    // Couldn't allocate outside the heap. Is the heap available?
+    if (!gc_alloc_possible()) {
         return false;
     }
 
@@ -414,7 +416,7 @@ static void release_ram_cache(void) {
     if (supervisor_cache != NULL) {
         free_memory(supervisor_cache);
         supervisor_cache = NULL;
-    } else if (MP_STATE_MEM(gc_pool_start)) {
+    } else if (gc_alloc_possible()) {
         m_free(MP_STATE_VM(flash_ram_cache));
     }
     MP_STATE_VM(flash_ram_cache) = NULL;
@@ -462,7 +464,7 @@ static bool flush_ram_cache(bool keep_cache) {
             write_flash(current_sector + (i * pages_per_block + j) * SPI_FLASH_PAGE_SIZE,
                 MP_STATE_VM(flash_ram_cache)[i * pages_per_block + j],
                 SPI_FLASH_PAGE_SIZE);
-            if (!keep_cache && supervisor_cache == NULL && MP_STATE_MEM(gc_pool_start)) {
+            if (!keep_cache && supervisor_cache == NULL && gc_alloc_possible()) {
                 m_free(MP_STATE_VM(flash_ram_cache)[i * pages_per_block + j]);
             }
         }