1 files changed, 2 insertions, 1 deletions
diff --git a/py/map.c b/py/map.c
index 933b5f8e29..5b9e803774 100644
--- a/py/map.c
+++ b/py/map.c
@@ -1,4 +1,5 @@
 #include <stdlib.h>
+#include <assert.h>
 
 #include "misc.h"
 #include "mpconfig.h"
@@ -285,7 +286,7 @@ mp_obj_t mp_set_lookup(mp_set_t *set, mp_obj_t index, mp_map_lookup_kind_t looku
 
 mp_obj_t mp_set_remove_first(mp_set_t *set) {
     for (uint pos = 0; pos < set->alloc; pos++) {
-        if (set->table[pos] != MP_OBJ_NULL && set->table[pos] != MP_OBJ_SENTINEL) {
+        if (MP_SET_SLOT_IS_FILLED(set, pos)) {
             mp_obj_t elem = set->table[pos];
             // delete element
             set->used--;