diff --git a/ports/atmel-samd/boards/arduino_nano_33_iot/mpconfigboard.mk b/ports/atmel-samd/boards/arduino_nano_33_iot/mpconfigboard.mk
index a61e321b29..c940bc02ef 100644
--- a/ports/atmel-samd/boards/arduino_nano_33_iot/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/arduino_nano_33_iot/mpconfigboard.mk
@@ -10,4 +10,5 @@ INTERNAL_FLASH_FILESYSTEM = 1
 LONGINT_IMPL = NONE
 CIRCUITPY_FULL_BUILD = 0
 
+CIRCUITPY_ONEWIREIO = 0
 CIRCUITPY_RAINBOWIO = 0
diff --git a/py/mpstate.h b/py/mpstate.h
index 2f9dafd925..964a04f300 100644
--- a/py/mpstate.h
+++ b/py/mpstate.h
@@ -140,14 +140,10 @@ typedef struct _mp_state_vm_t {
     #if MICROPY_KBD_EXCEPTION
     // exception object of type KeyboardInterrupt
     mp_obj_exception_t mp_kbd_exception;
-    // traceback object to store traceback
-    mp_obj_traceback_t mp_kbd_traceback;
     #endif
 
     // exception object of type ReloadException
     mp_obj_exception_t mp_reload_exception;
-    // traceback object to store traceback
-    mp_obj_traceback_t mp_reload_traceback;
 
     // dictionary with loaded modules (may be exposed as sys.modules)
     mp_obj_dict_t mp_loaded_modules_dict;
diff --git a/py/objexcept.c b/py/objexcept.c
index c7e5cb7675..b8d7692b18 100644
--- a/py/objexcept.c
+++ b/py/objexcept.c
@@ -166,15 +166,7 @@ mp_obj_t mp_obj_exception_make_new(const mp_obj_type_t *type, size_t n_args, siz
 
     // Populate the exception object
     o_exc->base.type = type;
-
-    // Try to allocate memory for the traceback, with fallback to emergency traceback object
-    o_exc->traceback = m_new_obj_maybe(mp_obj_traceback_t);
-    if (o_exc->traceback == NULL) {
-        o_exc->traceback = &MP_STATE_VM(mp_emergency_traceback_obj);
-    }
-
-    // Populate the traceback object
-    *o_exc->traceback = mp_const_empty_traceback_obj;
+    o_exc->traceback = (mp_obj_traceback_t *)&mp_const_empty_traceback_obj;
 
     mp_obj_tuple_t *o_tuple;
     if (n_args == 0) {
@@ -228,7 +220,7 @@ void mp_obj_exception_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
         // store/delete attribute
         if (attr == MP_QSTR___traceback__) {
             if (dest[1] == mp_const_none) {
-                self->traceback->data = NULL;
+                self->traceback = (mp_obj_traceback_t *)&mp_const_empty_traceback_obj;
             } else {
                 if (!mp_obj_is_type(dest[1], &mp_type_traceback)) {
                     mp_raise_TypeError(MP_ERROR_TEXT("invalid traceback"));
@@ -244,7 +236,7 @@ void mp_obj_exception_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
     } else if (attr == MP_QSTR_value && self->base.type == &mp_type_StopIteration) {
         dest[0] = mp_obj_exception_get_value(self_in);
     } else if (attr == MP_QSTR___traceback__) {
-        dest[0] = (self->traceback->data) ? MP_OBJ_FROM_PTR(self->traceback) : mp_const_none;
+        dest[0] = (self->traceback) ? MP_OBJ_FROM_PTR(self->traceback) : mp_const_none;
     #if MICROPY_CPYTHON_COMPAT
     } else if (mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(self->base.type), MP_OBJ_FROM_PTR(&mp_type_OSError))) {
         if (attr == MP_QSTR_errno) {
@@ -552,14 +544,23 @@ bool mp_obj_exception_match(mp_obj_t exc, mp_const_obj_t exc_type) {
 
 void mp_obj_exception_clear_traceback(mp_obj_t self_in) {
     mp_obj_exception_t *self = get_native_exception(self_in);
-    // just set the traceback to the null object
+    // just set the traceback to the empty traceback object
     // we don't want to call any memory management functions here
-    self->traceback->data = NULL;
+    self->traceback = (mp_obj_traceback_t *)&mp_const_empty_traceback_obj;
 }
 
 void mp_obj_exception_add_traceback(mp_obj_t self_in, qstr file, size_t line, qstr block) {
     mp_obj_exception_t *self = get_native_exception(self_in);
 
+    // Try to allocate memory for the traceback, with fallback to emergency traceback object
+
+    if (self->traceback == NULL || self->traceback == (mp_obj_traceback_t *)&mp_const_empty_traceback_obj) {
+        self->traceback = m_new_obj_maybe(mp_obj_traceback_t);
+        if (self->traceback == NULL) {
+            self->traceback = &MP_STATE_VM(mp_emergency_traceback_obj);
+        }
+    }
+
     // append this traceback info to traceback data
     // if memory allocation fails (eg because gc is locked), just return
 
@@ -613,7 +614,7 @@ void mp_obj_exception_add_traceback(mp_obj_t self_in, qstr file, size_t line, qs
 void mp_obj_exception_get_traceback(mp_obj_t self_in, size_t *n, size_t **values) {
     mp_obj_exception_t *self = get_native_exception(self_in);
 
-    if (self->traceback->data == NULL) {
+    if (self->traceback == NULL) {
         *n = 0;
         *values = NULL;
     } else {
diff --git a/py/runtime.c b/py/runtime.c
index ac02f7074c..1554a70231 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -80,14 +80,12 @@ void mp_init(void) {
     // initialise the exception object for raising KeyboardInterrupt
     MP_STATE_VM(mp_kbd_exception).base.type = &mp_type_KeyboardInterrupt;
     MP_STATE_VM(mp_kbd_exception).args = (mp_obj_tuple_t *)&mp_const_empty_tuple_obj;
-    MP_STATE_VM(mp_kbd_exception).traceback = &MP_STATE_VM(mp_kbd_traceback);
-    *MP_STATE_VM(mp_kbd_exception).traceback = mp_const_empty_traceback_obj;
+    MP_STATE_VM(mp_kbd_exception).traceback = (mp_obj_traceback_t *)&mp_const_empty_traceback_obj;
     #endif
 
     MP_STATE_VM(mp_reload_exception).base.type = &mp_type_ReloadException;
     MP_STATE_VM(mp_reload_exception).args = (mp_obj_tuple_t *)&mp_const_empty_tuple_obj;
-    MP_STATE_VM(mp_reload_exception).traceback = &MP_STATE_VM(mp_reload_traceback);
-    *MP_STATE_VM(mp_reload_exception).traceback = mp_const_empty_traceback_obj;
+    MP_STATE_VM(mp_reload_exception).traceback = (mp_obj_traceback_t *)&mp_const_empty_traceback_obj;
 
     // call port specific initialization if any
     #ifdef MICROPY_PORT_INIT_FUNC
diff --git a/py/scheduler.c b/py/scheduler.c
index 8e150f41ed..1fd5daeab1 100644
--- a/py/scheduler.c
+++ b/py/scheduler.c
@@ -42,7 +42,7 @@ void MICROPY_WRAP_MP_SCHED_EXCEPTION(mp_sched_exception)(mp_obj_t exc) {
 #if MICROPY_KBD_EXCEPTION
 // This function may be called asynchronously at any time so only do the bare minimum.
 void MICROPY_WRAP_MP_SCHED_KEYBOARD_INTERRUPT(mp_sched_keyboard_interrupt)(void) {
-    MP_STATE_VM(mp_kbd_exception).traceback->data = NULL;
+    MP_STATE_VM(mp_kbd_exception).traceback = (mp_obj_traceback_t *)&mp_const_empty_traceback_obj;
     mp_sched_exception(MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_kbd_exception)));
 }
 #endif