diff --git a/py/map.c b/py/map.c
index 82237381cc..906a1611f0 100644
--- a/py/map.c
+++ b/py/map.c
@@ -24,6 +24,7 @@
  * THE SOFTWARE.
  */
 
+#include <stdint.h>
 #include <stdlib.h>
 #include <assert.h>
 
@@ -35,10 +36,10 @@
 
 // approximatelly doubling primes; made with Mathematica command: Table[Prime[Floor[(1.7)^n]], {n, 3, 24}]
 // prefixed with zero for the empty case.
-STATIC int doubling_primes[] = {0, 7, 19, 43, 89, 179, 347, 647, 1229, 2297, 4243, 7829, 14347, 26017, 47149, 84947, 152443, 273253, 488399, 869927, 1547173, 2745121, 4861607};
+STATIC uint32_t doubling_primes[] = {0, 7, 19, 43, 89, 179, 347, 647, 1229, 2297, 4243, 7829, 14347, 26017, 47149, 84947, 152443, 273253, 488399, 869927, 1547173, 2745121, 4861607};
 
-STATIC int get_doubling_prime_greater_or_equal_to(int x) {
-    for (int i = 0; i < sizeof(doubling_primes) / sizeof(int); i++) {
+STATIC mp_uint_t get_doubling_prime_greater_or_equal_to(mp_uint_t x) {
+    for (int i = 0; i < MP_ARRAY_SIZE(doubling_primes); i++) {
         if (doubling_primes[i] >= x) {
             return doubling_primes[i];
         }
@@ -51,7 +52,7 @@ STATIC int get_doubling_prime_greater_or_equal_to(int x) {
 /******************************************************************************/
 /* map                                                                        */
 
-void mp_map_init(mp_map_t *map, int n) {
+void mp_map_init(mp_map_t *map, mp_uint_t n) {
     if (n == 0) {
         map->alloc = 0;
         map->table = NULL;
@@ -64,7 +65,7 @@ void mp_map_init(mp_map_t *map, int n) {
     map->table_is_fixed_array = 0;
 }
 
-void mp_map_init_fixed_table(mp_map_t *map, int n, const mp_obj_t *table) {
+void mp_map_init_fixed_table(mp_map_t *map, mp_uint_t n, const mp_obj_t *table) {
     map->alloc = n;
     map->used = n;
     map->all_keys_are_qstrs = 1;
@@ -72,7 +73,7 @@ void mp_map_init_fixed_table(mp_map_t *map, int n, const mp_obj_t *table) {
     map->table = (mp_map_elem_t*)table;
 }
 
-mp_map_t *mp_map_new(int n) {
+mp_map_t *mp_map_new(mp_uint_t n) {
     mp_map_t *map = m_new(mp_map_t, 1);
     mp_map_init(map, n);
     return map;
@@ -103,13 +104,13 @@ void mp_map_clear(mp_map_t *map) {
 }
 
 STATIC void mp_map_rehash(mp_map_t *map) {
-    int old_alloc = map->alloc;
+    mp_uint_t old_alloc = map->alloc;
     mp_map_elem_t *old_table = map->table;
     map->alloc = get_doubling_prime_greater_or_equal_to(map->alloc + 1);
     map->used = 0;
     map->all_keys_are_qstrs = 1;
     map->table = m_new0(mp_map_elem_t, map->alloc);
-    for (int i = 0; i < old_alloc; i++) {
+    for (mp_uint_t i = 0; i < old_alloc; i++) {
         if (old_table[i].key != MP_OBJ_NULL && old_table[i].key != MP_OBJ_SENTINEL) {
             mp_map_lookup(map, old_table[i].key, MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = old_table[i].value;
         }
@@ -168,8 +169,8 @@ mp_map_elem_t* mp_map_lookup(mp_map_t *map, mp_obj_t index, mp_map_lookup_kind_t
     }
 
     mp_uint_t hash = mp_obj_hash(index);
-    uint pos = hash % map->alloc;
-    uint start_pos = pos;
+    mp_uint_t pos = hash % map->alloc;
+    mp_uint_t start_pos = pos;
     mp_map_elem_t *avail_slot = NULL;
     for (;;) {
         mp_map_elem_t *slot = &map->table[pos];
@@ -242,19 +243,19 @@ mp_map_elem_t* mp_map_lookup(mp_map_t *map, mp_obj_t index, mp_map_lookup_kind_t
 /******************************************************************************/
 /* set                                                                        */
 
-void mp_set_init(mp_set_t *set, int n) {
+void mp_set_init(mp_set_t *set, mp_uint_t n) {
     set->alloc = n;
     set->used = 0;
     set->table = m_new0(mp_obj_t, set->alloc);
 }
 
 STATIC void mp_set_rehash(mp_set_t *set) {
-    int old_alloc = set->alloc;
+    mp_uint_t old_alloc = set->alloc;
     mp_obj_t *old_table = set->table;
     set->alloc = get_doubling_prime_greater_or_equal_to(set->alloc + 1);
     set->used = 0;
     set->table = m_new0(mp_obj_t, set->alloc);
-    for (int i = 0; i < old_alloc; i++) {
+    for (mp_uint_t i = 0; i < old_alloc; i++) {
         if (old_table[i] != MP_OBJ_NULL && old_table[i] != MP_OBJ_SENTINEL) {
             mp_set_lookup(set, old_table[i], MP_MAP_LOOKUP_ADD_IF_NOT_FOUND);
         }
@@ -271,8 +272,8 @@ mp_obj_t mp_set_lookup(mp_set_t *set, mp_obj_t index, mp_map_lookup_kind_t looku
         }
     }
     mp_uint_t hash = mp_obj_hash(index);
-    uint pos = hash % set->alloc;
-    uint start_pos = pos;
+    mp_uint_t pos = hash % set->alloc;
+    mp_uint_t start_pos = pos;
     mp_obj_t *avail_slot = NULL;
     for (;;) {
         mp_obj_t elem = set->table[pos];
@@ -333,7 +334,7 @@ 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++) {
+    for (mp_uint_t pos = 0; pos < set->alloc; pos++) {
         if (MP_SET_SLOT_IS_FILLED(set, pos)) {
             mp_obj_t elem = set->table[pos];
             // delete element
@@ -359,7 +360,7 @@ void mp_set_clear(mp_set_t *set) {
 
 #if DEBUG_PRINT
 void mp_map_dump(mp_map_t *map) {
-    for (int i = 0; i < map->alloc; i++) {
+    for (mp_uint_t i = 0; i < map->alloc; i++) {
         if (map->table[i].key != NULL) {
             mp_obj_print(map->table[i].key, PRINT_REPR);
         } else {
diff --git a/py/obj.h b/py/obj.h
index 0cb3d52d00..34a54d7d8c 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -150,9 +150,9 @@ typedef enum _mp_map_lookup_kind_t {
 
 static inline bool MP_MAP_SLOT_IS_FILLED(const mp_map_t *map, mp_uint_t pos) { return ((map)->table[pos].key != MP_OBJ_NULL && (map)->table[pos].key != MP_OBJ_SENTINEL); }
 
-void mp_map_init(mp_map_t *map, int n);
-void mp_map_init_fixed_table(mp_map_t *map, int n, const mp_obj_t *table);
-mp_map_t *mp_map_new(int n);
+void mp_map_init(mp_map_t *map, mp_uint_t n);
+void mp_map_init_fixed_table(mp_map_t *map, mp_uint_t n, const mp_obj_t *table);
+mp_map_t *mp_map_new(mp_uint_t n);
 void mp_map_deinit(mp_map_t *map);
 void mp_map_free(mp_map_t *map);
 mp_map_elem_t* mp_map_lookup(mp_map_t *map, mp_obj_t index, mp_map_lookup_kind_t lookup_kind);
@@ -169,7 +169,7 @@ typedef struct _mp_set_t {
 
 static inline bool MP_SET_SLOT_IS_FILLED(const mp_set_t *set, mp_uint_t pos) { return ((set)->table[pos] != MP_OBJ_NULL && (set)->table[pos] != MP_OBJ_SENTINEL); }
 
-void mp_set_init(mp_set_t *set, int n);
+void mp_set_init(mp_set_t *set, mp_uint_t n);
 mp_obj_t mp_set_lookup(mp_set_t *set, mp_obj_t index, mp_map_lookup_kind_t lookup_kind);
 mp_obj_t mp_set_remove_first(mp_set_t *set);
 void mp_set_clear(mp_set_t *set);
@@ -386,8 +386,8 @@ mp_obj_t mp_obj_new_gen_wrap(mp_obj_t fun);
 mp_obj_t mp_obj_new_closure(mp_obj_t fun, uint n_closed, const mp_obj_t *closed);
 mp_obj_t mp_obj_new_tuple(uint n, const mp_obj_t *items);
 mp_obj_t mp_obj_new_list(uint n, mp_obj_t *items);
-mp_obj_t mp_obj_new_dict(int n_args);
-mp_obj_t mp_obj_new_set(int n_args, mp_obj_t *items);
+mp_obj_t mp_obj_new_dict(mp_uint_t n_args);
+mp_obj_t mp_obj_new_set(mp_uint_t n_args, mp_obj_t *items);
 mp_obj_t mp_obj_new_slice(mp_obj_t start, mp_obj_t stop, mp_obj_t step);
 mp_obj_t mp_obj_new_super(mp_obj_t type, mp_obj_t obj);
 mp_obj_t mp_obj_new_bound_meth(mp_obj_t meth, mp_obj_t self);
@@ -508,8 +508,8 @@ typedef struct _mp_obj_dict_t {
     mp_obj_base_t base;
     mp_map_t map;
 } mp_obj_dict_t;
-void mp_obj_dict_init(mp_obj_dict_t *dict, int n_args);
-uint mp_obj_dict_len(mp_obj_t self_in);
+void mp_obj_dict_init(mp_obj_dict_t *dict, mp_uint_t n_args);
+mp_uint_t mp_obj_dict_len(mp_obj_t self_in);
 mp_obj_t mp_obj_dict_get(mp_obj_t self_in, mp_obj_t index);
 mp_obj_t mp_obj_dict_store(mp_obj_t self_in, mp_obj_t key, mp_obj_t value);
 mp_obj_t mp_obj_dict_delete(mp_obj_t self_in, mp_obj_t key);
diff --git a/py/objdict.c b/py/objdict.c
index a755c17f72..d25cb4b377 100644
--- a/py/objdict.c
+++ b/py/objdict.c
@@ -38,9 +38,9 @@
 #include "runtime.h"
 #include "builtin.h"
 
-STATIC mp_obj_t mp_obj_new_dict_iterator(mp_obj_dict_t *dict, int cur);
+STATIC mp_obj_t mp_obj_new_dict_iterator(mp_obj_dict_t *dict, mp_uint_t cur);
 STATIC mp_map_elem_t *dict_it_iternext_elem(mp_obj_t self_in);
-STATIC mp_obj_t dict_update(uint n_args, const mp_obj_t *args, mp_map_t *kwargs);
+STATIC mp_obj_t dict_update(mp_uint_t n_args, const mp_obj_t *args, mp_map_t *kwargs);
 
 STATIC void dict_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in, mp_print_kind_t kind) {
     mp_obj_dict_t *self = self_in;
@@ -163,7 +163,7 @@ STATIC mp_map_elem_t *dict_it_iternext_elem(mp_obj_t self_in) {
     mp_uint_t max = self->dict->map.alloc;
     mp_map_t *map = &self->dict->map;
 
-    for (int i = self->cur; i < max; i++) {
+    for (mp_uint_t i = self->cur; i < max; i++) {
         if (MP_MAP_SLOT_IS_FILLED(map, i)) {
             self->cur = i + 1;
             return &(map->table[i]);
@@ -190,7 +190,7 @@ STATIC const mp_obj_type_t mp_type_dict_it = {
     .iternext = dict_it_iternext,
 };
 
-STATIC mp_obj_t mp_obj_new_dict_iterator(mp_obj_dict_t *dict, int cur) {
+STATIC mp_obj_t mp_obj_new_dict_iterator(mp_obj_dict_t *dict, mp_uint_t cur) {
     mp_obj_dict_it_t *o = m_new_obj(mp_obj_dict_it_t);
     o->base.type = &mp_type_dict_it;
     o->dict = dict;
@@ -228,7 +228,7 @@ STATIC mp_obj_t dict_copy(mp_obj_t self_in) {
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(dict_copy_obj, dict_copy);
 
 // this is a classmethod
-STATIC mp_obj_t dict_fromkeys(uint n_args, const mp_obj_t *args) {
+STATIC mp_obj_t dict_fromkeys(mp_uint_t n_args, const mp_obj_t *args) {
     assert(2 <= n_args && n_args <= 3);
     mp_obj_t iter = mp_getiter(args[1]);
     mp_obj_t len = mp_obj_len_maybe(iter);
@@ -278,7 +278,7 @@ STATIC mp_obj_t dict_get_helper(mp_map_t *self, mp_obj_t key, mp_obj_t deflt, mp
     return value;
 }
 
-STATIC mp_obj_t dict_get(uint n_args, const mp_obj_t *args) {
+STATIC mp_obj_t dict_get(mp_uint_t n_args, const mp_obj_t *args) {
     assert(2 <= n_args && n_args <= 3);
     assert(MP_OBJ_IS_TYPE(args[0], &mp_type_dict));
 
@@ -289,7 +289,7 @@ STATIC mp_obj_t dict_get(uint n_args, const mp_obj_t *args) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(dict_get_obj, 2, 3, dict_get);
 
-STATIC mp_obj_t dict_pop(uint n_args, const mp_obj_t *args) {
+STATIC mp_obj_t dict_pop(mp_uint_t n_args, const mp_obj_t *args) {
     assert(2 <= n_args && n_args <= 3);
     assert(MP_OBJ_IS_TYPE(args[0], &mp_type_dict));
 
@@ -301,7 +301,7 @@ STATIC mp_obj_t dict_pop(uint n_args, const mp_obj_t *args) {
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(dict_pop_obj, 2, 3, dict_pop);
 
 
-STATIC mp_obj_t dict_setdefault(uint n_args, const mp_obj_t *args) {
+STATIC mp_obj_t dict_setdefault(mp_uint_t n_args, const mp_obj_t *args) {
     assert(2 <= n_args && n_args <= 3);
     assert(MP_OBJ_IS_TYPE(args[0], &mp_type_dict));
 
@@ -332,7 +332,7 @@ STATIC mp_obj_t dict_popitem(mp_obj_t self_in) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(dict_popitem_obj, dict_popitem);
 
-STATIC mp_obj_t dict_update(uint n_args, const mp_obj_t *args, mp_map_t *kwargs) {
+STATIC mp_obj_t dict_update(mp_uint_t n_args, const mp_obj_t *args, mp_map_t *kwargs) {
     assert(MP_OBJ_IS_TYPE(args[0], &mp_type_dict));
     mp_obj_dict_t *self = args[0];
 
@@ -555,18 +555,18 @@ const mp_obj_type_t mp_type_dict = {
     .locals_dict = (mp_obj_t)&dict_locals_dict,
 };
 
-void mp_obj_dict_init(mp_obj_dict_t *dict, int n_args) {
+void mp_obj_dict_init(mp_obj_dict_t *dict, mp_uint_t n_args) {
     dict->base.type = &mp_type_dict;
     mp_map_init(&dict->map, n_args);
 }
 
-mp_obj_t mp_obj_new_dict(int n_args) {
+mp_obj_t mp_obj_new_dict(mp_uint_t n_args) {
     mp_obj_dict_t *o = m_new_obj(mp_obj_dict_t);
     mp_obj_dict_init(o, n_args);
     return o;
 }
 
-uint mp_obj_dict_len(mp_obj_t self_in) {
+mp_uint_t mp_obj_dict_len(mp_obj_t self_in) {
     return ((mp_obj_dict_t *)self_in)->map.used;
 }
 
diff --git a/py/objset.c b/py/objset.c
index 1184bef93b..1069cd5eac 100644
--- a/py/objset.c
+++ b/py/objset.c
@@ -104,7 +104,7 @@ STATIC void set_print(void (*print)(void *env, const char *fmt, ...), void *env,
     }
     #endif
     print(env, "{");
-    for (int i = 0; i < self->set.alloc; i++) {
+    for (mp_uint_t i = 0; i < self->set.alloc; i++) {
         if (MP_SET_SLOT_IS_FILLED(&self->set, i)) {
             if (!first) {
                 print(env, ", ");
@@ -247,7 +247,7 @@ STATIC mp_obj_t set_diff_int(mp_uint_t n_args, const mp_obj_t *args, bool update
     }
 
 
-    for (int i = 1; i < n_args; i++) {
+    for (mp_uint_t i = 1; i < n_args; i++) {
         mp_obj_t other = args[i];
         if (self == other) {
             set_clear(self);
@@ -456,7 +456,7 @@ STATIC void set_update_int(mp_obj_set_t *self, mp_obj_t other_in) {
 STATIC mp_obj_t set_update(mp_uint_t n_args, const mp_obj_t *args) {
     assert(n_args > 0);
 
-    for (int i = 1; i < n_args; i++) {
+    for (mp_uint_t i = 1; i < n_args; i++) {
         set_update_int(args[0], args[i]);
     }
 
@@ -571,11 +571,11 @@ const mp_obj_type_t mp_type_frozenset = {
 };
 #endif
 
-mp_obj_t mp_obj_new_set(int n_args, mp_obj_t *items) {
+mp_obj_t mp_obj_new_set(mp_uint_t n_args, mp_obj_t *items) {
     mp_obj_set_t *o = m_new_obj(mp_obj_set_t);
     o->base.type = &mp_type_set;
     mp_set_init(&o->set, n_args);
-    for (int i = 0; i < n_args; i++) {
+    for (mp_uint_t i = 0; i < n_args; i++) {
         mp_set_lookup(&o->set, items[i], MP_MAP_LOOKUP_ADD_IF_NOT_FOUND);
     }
     return o;