diff --git a/ports/mimxrt10xx/supervisor/port.c b/ports/mimxrt10xx/supervisor/port.c
index 18cb408cb0..b6ae002930 100644
--- a/ports/mimxrt10xx/supervisor/port.c
+++ b/ports/mimxrt10xx/supervisor/port.c
@@ -318,6 +318,10 @@ void reset_cpu(void) {
     reset();
 }
 
+supervisor_allocation* port_fixed_stack(void) {
+    return NULL;
+}
+
 extern uint32_t _ld_heap_start, _ld_heap_end, _ld_stack_top, _ld_stack_bottom;
 uint32_t *port_stack_get_limit(void) {
     return &_ld_heap_start;
diff --git a/ports/nrf/supervisor/port.c b/ports/nrf/supervisor/port.c
index 539a9cf90b..87632fa4dd 100644
--- a/ports/nrf/supervisor/port.c
+++ b/ports/nrf/supervisor/port.c
@@ -185,6 +185,10 @@ uint32_t *port_heap_get_top(void) {
     return port_stack_get_top();
 }
 
+supervisor_allocation* port_fixed_stack(void) {
+    return NULL;
+}
+
 uint32_t *port_stack_get_limit(void) {
     return &_ebss;
 }
diff --git a/ports/stm/supervisor/port.c b/ports/stm/supervisor/port.c
index 23ba7d8745..9b62fa2eb1 100644
--- a/ports/stm/supervisor/port.c
+++ b/ports/stm/supervisor/port.c
@@ -176,7 +176,7 @@ safe_mode_t port_init(void) {
     uint32_t tickstart = HAL_GetTick();
 
     // H7/F7 untested with LSE, so autofail them until above move is done
-    #if (CPY_STM32F4) 
+    #if (CPY_STM32F4)
     bool lse_setupsuccess = true;
     #else
     bool lse_setupsuccess = false;
@@ -281,6 +281,10 @@ uint32_t *port_heap_get_top(void) {
     return &_ld_heap_end;
 }
 
+supervisor_allocation* port_fixed_stack(void) {
+    return NULL;
+}
+
 uint32_t *port_stack_get_limit(void) {
     return &_ld_stack_bottom;
 }