diff --git a/py/modbuiltins.c b/py/modbuiltins.c
index 5377411..05bdbfe 100644
--- a/py/modbuiltins.c
+++ b/py/modbuiltins.c
@@ -512,7 +512,7 @@
         nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
                                           "must use keyword argument for key function"));
     }
-    mp_obj_t self = mp_type_list.make_new(MP_OBJ_FROM_PTR(&mp_type_list), 1, 0, args);
+    mp_obj_t self = mp_type_list.make_new(&mp_type_list, 1, 0, args);
     mp_obj_list_sort(1, &self, kwargs);
 
     return self;
diff --git a/py/obj.h b/py/obj.h
index 52b8b4f..14c3a81 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -42,12 +42,14 @@
 typedef machine_const_ptr_t mp_const_obj_t;
 #endif
 
-// Anything that wants to be a Micro Python object must have
-// mp_obj_base_t as its first member (except small ints and qstrs)
+// This mp_obj_type_t struct is a concrete MicroPython object which holds info
+// about a type.  See below for actual definition of the struct.
+typedef struct _mp_obj_type_t mp_obj_type_t;
 
-struct _mp_obj_type_t;
+// Anything that wants to be a concrete MicroPython object must have mp_obj_base_t
+// as its first member (small ints, qstr objs and inline floats are not concrete).
 struct _mp_obj_base_t {
-    const struct _mp_obj_type_t *type MICROPY_OBJ_BASE_ALIGNMENT;
+    const mp_obj_type_t *type MICROPY_OBJ_BASE_ALIGNMENT;
 };
 typedef struct _mp_obj_base_t mp_obj_base_t;
 
@@ -259,8 +261,8 @@
 //static inline bool MP_OBJ_IS_TYPE(mp_const_obj_t o, const mp_obj_type_t *t) { return (MP_OBJ_IS_OBJ(o) && (((mp_obj_base_t*)(o))->type == (t))); } // this does not work for checking a string, use below macro for that
 //static inline bool MP_OBJ_IS_INT(mp_const_obj_t o) { return (MP_OBJ_IS_SMALL_INT(o) || MP_OBJ_IS_TYPE(o, &mp_type_int)); } // returns true if o is a small int or long int
 // Need to forward declare these for the inline function to compile.
-extern const struct _mp_obj_type_t mp_type_int;
-extern const struct _mp_obj_type_t mp_type_bool;
+extern const mp_obj_type_t mp_type_int;
+extern const mp_obj_type_t mp_type_bool;
 static inline bool mp_obj_is_integer(mp_const_obj_t o) { return MP_OBJ_IS_INT(o) || MP_OBJ_IS_TYPE(o, &mp_type_bool); } // returns true if o is bool, small int or long int
 //static inline bool MP_OBJ_IS_STR(mp_const_obj_t o) { return (MP_OBJ_IS_QSTR(o) || MP_OBJ_IS_TYPE(o, &mp_type_str)); }
 
@@ -408,7 +410,7 @@
 } mp_print_kind_t;
 
 typedef void (*mp_print_fun_t)(const mp_print_t *print, mp_obj_t o, mp_print_kind_t kind);
-typedef mp_obj_t (*mp_make_new_fun_t)(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args);
+typedef mp_obj_t (*mp_make_new_fun_t)(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args);
 typedef mp_obj_t (*mp_call_fun_t)(mp_obj_t fun, size_t n_args, size_t n_kw, const mp_obj_t *args);
 typedef mp_obj_t (*mp_unary_op_fun_t)(mp_uint_t op, mp_obj_t);
 typedef mp_obj_t (*mp_binary_op_fun_t)(mp_uint_t op, mp_obj_t, mp_obj_t);
@@ -510,8 +512,6 @@
     */
 };
 
-typedef struct _mp_obj_type_t mp_obj_type_t;
-
 // Constant types, globally accessible
 extern const mp_obj_type_t mp_type_type;
 extern const mp_obj_type_t mp_type_object;
@@ -691,7 +691,7 @@
 void mp_obj_exception_add_traceback(mp_obj_t self_in, qstr file, size_t line, qstr block);
 void mp_obj_exception_get_traceback(mp_obj_t self_in, size_t *n, size_t **values);
 mp_obj_t mp_obj_exception_get_value(mp_obj_t self_in);
-mp_obj_t mp_obj_exception_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args);
+mp_obj_t mp_obj_exception_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args);
 mp_obj_t mp_alloc_emergency_exception_buf(mp_obj_t size_in);
 void mp_init_emergency_exception_buf(void);
 
diff --git a/py/objarray.c b/py/objarray.c
index 2c4813f..a17ae27 100644
--- a/py/objarray.c
+++ b/py/objarray.c
@@ -168,7 +168,7 @@
 #endif
 
 #if MICROPY_PY_ARRAY
-STATIC mp_obj_t array_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t array_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     (void)type_in;
     mp_arg_check_num(n_args, n_kw, 1, 2, false);
 
@@ -187,7 +187,7 @@
 #endif
 
 #if MICROPY_PY_BUILTINS_BYTEARRAY
-STATIC mp_obj_t bytearray_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t bytearray_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     (void)type_in;
     mp_arg_check_num(n_args, n_kw, 0, 1, false);
 
@@ -219,7 +219,7 @@
     return MP_OBJ_FROM_PTR(self);
 }
 
-STATIC mp_obj_t memoryview_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t memoryview_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     (void)type_in;
 
     // TODO possibly allow memoryview constructor to take start/stop so that one
diff --git a/py/objbool.c b/py/objbool.c
index 09878a7..8882a83 100644
--- a/py/objbool.c
+++ b/py/objbool.c
@@ -52,7 +52,7 @@
     }
 }
 
-STATIC mp_obj_t bool_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t bool_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     (void)type_in;
     mp_arg_check_num(n_args, n_kw, 0, 1, false);
 
diff --git a/py/objcomplex.c b/py/objcomplex.c
index df0467e..5da655e 100644
--- a/py/objcomplex.c
+++ b/py/objcomplex.c
@@ -69,7 +69,7 @@
     }
 }
 
-STATIC mp_obj_t complex_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t complex_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     (void)type_in;
     mp_arg_check_num(n_args, n_kw, 0, 2, false);
 
diff --git a/py/objdict.c b/py/objdict.c
index cb4c602..cc1f502 100644
--- a/py/objdict.c
+++ b/py/objdict.c
@@ -82,12 +82,12 @@
     }
 }
 
-STATIC mp_obj_t dict_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t dict_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     mp_obj_t dict_out = mp_obj_new_dict(0);
     mp_obj_dict_t *dict = MP_OBJ_TO_PTR(dict_out);
-    dict->base.type = MP_OBJ_TO_PTR(type_in);
+    dict->base.type = type;
     #if MICROPY_PY_COLLECTIONS_ORDEREDDICT
-    if (MP_OBJ_TO_PTR(type_in) == &mp_type_ordereddict) {
+    if (type == &mp_type_ordereddict) {
         dict->map.is_ordered = 1;
     }
     #endif
diff --git a/py/objenumerate.c b/py/objenumerate.c
index 46c3e80..26a5740 100644
--- a/py/objenumerate.c
+++ b/py/objenumerate.c
@@ -45,7 +45,7 @@
 };
 #define ENUMERATE_MAKE_NEW_NUM_ARGS MP_ARRAY_SIZE(enumerate_make_new_args)
 
-STATIC mp_obj_t enumerate_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t enumerate_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
 #if MICROPY_CPYTHON_COMPAT
     // parse args
     mp_arg_val_t vals[ENUMERATE_MAKE_NEW_NUM_ARGS];
@@ -53,13 +53,13 @@
 
     // create enumerate object
     mp_obj_enumerate_t *o = m_new_obj(mp_obj_enumerate_t);
-    o->base.type = MP_OBJ_TO_PTR(type_in);
+    o->base.type = type;
     o->iter = mp_getiter(vals[0].u_obj);
     o->cur = vals[1].u_int;
 #else
     (void)n_kw;
     mp_obj_enumerate_t *o = m_new_obj(mp_obj_enumerate_t);
-    o->base.type = type_in;
+    o->base.type = type;
     o->iter = mp_getiter(args[0]);
     o->cur = n_args > 1 ? mp_obj_get_int(args[1]) : 0;
 #endif
diff --git a/py/objexcept.c b/py/objexcept.c
index 83aa528..d8aecb8 100644
--- a/py/objexcept.c
+++ b/py/objexcept.c
@@ -114,7 +114,7 @@
     mp_obj_tuple_print(print, MP_OBJ_FROM_PTR(o->args), kind);
 }
 
-mp_obj_t mp_obj_exception_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+mp_obj_t mp_obj_exception_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     mp_arg_check_num(n_args, n_kw, 0, MP_OBJ_FUN_ARGS_MAX, false);
     mp_obj_exception_t *o = m_new_obj_var_maybe(mp_obj_exception_t, mp_obj_t, 0);
     if (o == NULL) {
@@ -125,7 +125,7 @@
     } else {
         o->args = MP_OBJ_TO_PTR(mp_obj_new_tuple(n_args, args));
     }
-    o->base.type = MP_OBJ_TO_PTR(type_in);
+    o->base.type = type;
     o->traceback_data = NULL;
     return MP_OBJ_FROM_PTR(o);
 }
@@ -290,7 +290,7 @@
 
 mp_obj_t mp_obj_new_exception_args(const mp_obj_type_t *exc_type, mp_uint_t n_args, const mp_obj_t *args) {
     assert(exc_type->make_new == mp_obj_exception_make_new);
-    return exc_type->make_new(MP_OBJ_FROM_PTR(exc_type), n_args, 0, args);
+    return exc_type->make_new(exc_type, n_args, 0, args);
 }
 
 mp_obj_t mp_obj_new_exception_msg(const mp_obj_type_t *exc_type, const char *msg) {
diff --git a/py/objfilter.c b/py/objfilter.c
index 168f0e7..e288102 100644
--- a/py/objfilter.c
+++ b/py/objfilter.c
@@ -34,10 +34,10 @@
     mp_obj_t iter;
 } mp_obj_filter_t;
 
-STATIC mp_obj_t filter_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t filter_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     mp_arg_check_num(n_args, n_kw, 2, 2, false);
     mp_obj_filter_t *o = m_new_obj(mp_obj_filter_t);
-    o->base.type = MP_OBJ_TO_PTR(type_in);
+    o->base.type = type;
     o->fun = args[0];
     o->iter = mp_getiter(args[1]);
     return MP_OBJ_FROM_PTR(o);
diff --git a/py/objfloat.c b/py/objfloat.c
index f144bfd..aa37f9a 100644
--- a/py/objfloat.c
+++ b/py/objfloat.c
@@ -69,7 +69,7 @@
     }
 }
 
-STATIC mp_obj_t float_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t float_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     (void)type_in;
     mp_arg_check_num(n_args, n_kw, 0, 1, false);
 
diff --git a/py/objint.c b/py/objint.c
index e548eb8..46290a3 100644
--- a/py/objint.c
+++ b/py/objint.c
@@ -42,7 +42,7 @@
 #endif
 
 // This dispatcher function is expected to be independent of the implementation of long int
-STATIC mp_obj_t mp_obj_int_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t mp_obj_int_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     (void)type_in;
     mp_arg_check_num(n_args, n_kw, 0, 2, false);
 
diff --git a/py/objlist.c b/py/objlist.c
index 3fd38e8..62928af 100644
--- a/py/objlist.c
+++ b/py/objlist.c
@@ -68,7 +68,7 @@
     return list;
 }
 
-STATIC mp_obj_t list_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t list_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     (void)type_in;
     mp_arg_check_num(n_args, n_kw, 0, 1, false);
 
diff --git a/py/objmap.c b/py/objmap.c
index a0293c3..526bc05 100644
--- a/py/objmap.c
+++ b/py/objmap.c
@@ -36,10 +36,10 @@
     mp_obj_t iters[];
 } mp_obj_map_t;
 
-STATIC mp_obj_t map_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t map_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     mp_arg_check_num(n_args, n_kw, 2, MP_OBJ_FUN_ARGS_MAX, false);
     mp_obj_map_t *o = m_new_obj_var(mp_obj_map_t, mp_obj_t, n_args - 1);
-    o->base.type = MP_OBJ_TO_PTR(type_in);
+    o->base.type = type;
     o->n_iters = n_args - 1;
     o->fun = args[0];
     for (mp_uint_t i = 0; i < n_args - 1; i++) {
diff --git a/py/objnamedtuple.c b/py/objnamedtuple.c
index 3e34603..62289f5 100644
--- a/py/objnamedtuple.c
+++ b/py/objnamedtuple.c
@@ -44,7 +44,7 @@
     mp_obj_tuple_t tuple;
 } mp_obj_namedtuple_t;
 
-STATIC mp_uint_t namedtuple_find_field(mp_obj_namedtuple_type_t *type, qstr name) {
+STATIC mp_uint_t namedtuple_find_field(const mp_obj_namedtuple_type_t *type, qstr name) {
     for (mp_uint_t i = 0; i < type->n_fields; i++) {
         if (type->fields[i] == name) {
             return i;
@@ -77,8 +77,8 @@
     }
 }
 
-STATIC mp_obj_t namedtuple_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
-    mp_obj_namedtuple_type_t *type = MP_OBJ_TO_PTR(type_in);
+STATIC mp_obj_t namedtuple_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+    const mp_obj_namedtuple_type_t *type = (const mp_obj_namedtuple_type_t*)type_in;
     mp_uint_t num_fields = type->n_fields;
     if (n_args + n_kw != num_fields) {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
@@ -130,7 +130,7 @@
     }
 
     mp_obj_tuple_t *tuple = MP_OBJ_TO_PTR(mp_obj_new_tuple(num_fields, arg_objects));
-    tuple->base.type = MP_OBJ_TO_PTR(type_in);
+    tuple->base.type = type_in;
     return MP_OBJ_FROM_PTR(tuple);
 }
 
diff --git a/py/objobject.c b/py/objobject.c
index 5cd3773..bba6f05 100644
--- a/py/objobject.c
+++ b/py/objobject.c
@@ -33,11 +33,11 @@
     mp_obj_base_t base;
 } mp_obj_object_t;
 
-STATIC mp_obj_t object_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t object_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     (void)args;
     mp_arg_check_num(n_args, n_kw, 0, 0, false);
     mp_obj_object_t *o = m_new_obj(mp_obj_object_t);
-    o->base.type = MP_OBJ_TO_PTR(type_in);
+    o->base.type = type;
     return MP_OBJ_FROM_PTR(o);
 }
 
@@ -54,7 +54,7 @@
                     "__new__ arg must be a user-type"));
     }
     mp_obj_t o = MP_OBJ_SENTINEL;
-    mp_obj_t res = mp_obj_instance_make_new(cls, 1, 0, &o);
+    mp_obj_t res = mp_obj_instance_make_new(MP_OBJ_TO_PTR(cls), 1, 0, &o);
     return res;
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(object___new___fun_obj, object___new__);
diff --git a/py/objproperty.c b/py/objproperty.c
index 323696c..80e39e0 100644
--- a/py/objproperty.c
+++ b/py/objproperty.c
@@ -37,11 +37,11 @@
     mp_obj_t proxy[3]; // getter, setter, deleter
 } mp_obj_property_t;
 
-STATIC mp_obj_t property_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t property_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     mp_arg_check_num(n_args, n_kw, 0, 4, false);
 
     mp_obj_property_t *o = m_new_obj(mp_obj_property_t);
-    o->base.type = MP_OBJ_TO_PTR(type_in);
+    o->base.type = type;
     if (n_args >= 4) {
         // doc ignored
     }
diff --git a/py/objrange.c b/py/objrange.c
index bec026f..7945931 100644
--- a/py/objrange.c
+++ b/py/objrange.c
@@ -90,11 +90,11 @@
     }
 }
 
-STATIC mp_obj_t range_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t range_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     mp_arg_check_num(n_args, n_kw, 1, 3, false);
 
     mp_obj_range_t *o = m_new_obj(mp_obj_range_t);
-    o->base.type = MP_OBJ_TO_PTR(type_in);
+    o->base.type = type;
     o->start = 0;
     o->step = 1;
 
diff --git a/py/objreversed.c b/py/objreversed.c
index b0da00a..1e54bb5 100644
--- a/py/objreversed.c
+++ b/py/objreversed.c
@@ -38,7 +38,7 @@
     mp_uint_t cur_index;    // current index, plus 1; 0=no more, 1=last one (index 0)
 } mp_obj_reversed_t;
 
-STATIC mp_obj_t reversed_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t reversed_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     mp_arg_check_num(n_args, n_kw, 1, 1, false);
 
     // check if __reversed__ exists, and if so delegate to it
@@ -49,7 +49,7 @@
     }
 
     mp_obj_reversed_t *o = m_new_obj(mp_obj_reversed_t);
-    o->base.type = MP_OBJ_TO_PTR(type_in);
+    o->base.type = type;
     o->seq = args[0];
     o->cur_index = mp_obj_get_int(mp_obj_len(args[0])); // start at the end of the sequence
 
diff --git a/py/objset.c b/py/objset.c
index c83212c..8730918 100644
--- a/py/objset.c
+++ b/py/objset.c
@@ -119,7 +119,7 @@
     #endif
 }
 
-STATIC mp_obj_t set_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t set_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     mp_arg_check_num(n_args, n_kw, 0, 1, false);
 
     switch (n_args) {
@@ -127,7 +127,7 @@
             // create a new, empty set
             mp_obj_set_t *set = MP_OBJ_TO_PTR(mp_obj_new_set(0, NULL));
             // set actual set/frozenset type
-            set->base.type = MP_OBJ_TO_PTR(type_in);
+            set->base.type = type;
             return MP_OBJ_FROM_PTR(set);
         }
 
@@ -141,7 +141,7 @@
                 mp_obj_set_store(set, item);
             }
             // Set actual set/frozenset type
-            ((mp_obj_set_t*)MP_OBJ_TO_PTR(set))->base.type = MP_OBJ_TO_PTR(type_in);
+            ((mp_obj_set_t*)MP_OBJ_TO_PTR(set))->base.type = type;
             return set;
         }
     }
@@ -327,7 +327,7 @@
     if (is_set_or_frozenset(self_in)) {
         self = MP_OBJ_TO_PTR(self_in);
     } else {
-        self = MP_OBJ_TO_PTR(set_make_new(MP_OBJ_FROM_PTR(&mp_type_set), 1, 0, &self_in));
+        self = MP_OBJ_TO_PTR(set_make_new(&mp_type_set, 1, 0, &self_in));
         cleanup_self = true;
     }
 
@@ -336,7 +336,7 @@
     if (is_set_or_frozenset(other_in)) {
         other = MP_OBJ_TO_PTR(other_in);
     } else {
-        other = MP_OBJ_TO_PTR(set_make_new(MP_OBJ_FROM_PTR(&mp_type_set), 1, 0, &other_in));
+        other = MP_OBJ_TO_PTR(set_make_new(&mp_type_set, 1, 0, &other_in));
         cleanup_other = true;
     }
     bool out = true;
diff --git a/py/objstr.c b/py/objstr.c
index a76ff0d..8a0a19d 100644
--- a/py/objstr.c
+++ b/py/objstr.c
@@ -131,7 +131,7 @@
     }
 }
 
-mp_obj_t mp_obj_str_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+mp_obj_t mp_obj_str_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
 #if MICROPY_CPYTHON_COMPAT
     if (n_kw != 0) {
         mp_arg_error_unimpl_kw();
@@ -149,7 +149,7 @@
             mp_print_t print;
             vstr_init_print(&vstr, 16, &print);
             mp_obj_print_helper(&print, args[0], PRINT_STR);
-            return mp_obj_new_str_from_vstr(MP_OBJ_TO_PTR(type_in), &vstr);
+            return mp_obj_new_str_from_vstr(type, &vstr);
         }
 
         default: // 2 or 3 args
@@ -157,7 +157,7 @@
             if (MP_OBJ_IS_TYPE(args[0], &mp_type_bytes)) {
                 GET_STR_DATA_LEN(args[0], str_data, str_len);
                 GET_STR_HASH(args[0], str_hash);
-                mp_obj_str_t *o = MP_OBJ_TO_PTR(mp_obj_new_str_of_type(MP_OBJ_TO_PTR(type_in), NULL, str_len));
+                mp_obj_str_t *o = MP_OBJ_TO_PTR(mp_obj_new_str_of_type(type, NULL, str_len));
                 o->data = str_data;
                 o->hash = str_hash;
                 return MP_OBJ_FROM_PTR(o);
@@ -169,7 +169,7 @@
     }
 }
 
-STATIC mp_obj_t bytes_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t bytes_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     (void)type_in;
 
     #if MICROPY_CPYTHON_COMPAT
@@ -426,7 +426,7 @@
         if (!MP_OBJ_IS_TYPE(arg, &mp_type_list)) {
             // arg is not a list, try to convert it to one
             // TODO: Try to optimize?
-            arg = mp_type_list.make_new(MP_OBJ_FROM_PTR(&mp_type_list), 1, 0, &arg);
+            arg = mp_type_list.make_new(&mp_type_list, 1, 0, &arg);
         }
         mp_obj_list_get(arg, &seq_len, &seq_items);
     }
@@ -1767,7 +1767,7 @@
         args = new_args;
         n_args++;
     }
-    return mp_obj_str_make_new(MP_OBJ_FROM_PTR(&mp_type_str), n_args, 0, args);
+    return mp_obj_str_make_new(&mp_type_str, n_args, 0, args);
 }
 
 // TODO: should accept kwargs too
@@ -1779,7 +1779,7 @@
         args = new_args;
         n_args++;
     }
-    return bytes_make_new(MP_OBJ_NULL, n_args, 0, args);
+    return bytes_make_new(NULL, n_args, 0, args);
 }
 #endif
 
diff --git a/py/objstr.h b/py/objstr.h
index 1cfb195..6179a74 100644
--- a/py/objstr.h
+++ b/py/objstr.h
@@ -60,7 +60,7 @@
     else { str_len = ((mp_obj_str_t*)MP_OBJ_TO_PTR(str_obj_in))->len; str_data = ((mp_obj_str_t*)MP_OBJ_TO_PTR(str_obj_in))->data; }
 #endif
 
-mp_obj_t mp_obj_str_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args);
+mp_obj_t mp_obj_str_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args);
 void mp_str_print_json(const mp_print_t *print, const byte *str_data, size_t str_len);
 mp_obj_t mp_obj_str_format(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs);
 mp_obj_t mp_obj_str_split(size_t n_args, const mp_obj_t *args);
diff --git a/py/objstringio.c b/py/objstringio.c
index 357320c..f50abfb 100644
--- a/py/objstringio.c
+++ b/py/objstringio.c
@@ -120,15 +120,15 @@
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(stringio___exit___obj, 4, 4, stringio___exit__);
 
-STATIC mp_obj_stringio_t *stringio_new(mp_obj_t type_in) {
+STATIC mp_obj_stringio_t *stringio_new(const mp_obj_type_t *type) {
     mp_obj_stringio_t *o = m_new_obj(mp_obj_stringio_t);
-    o->base.type = MP_OBJ_TO_PTR(type_in);
+    o->base.type = type;
     o->vstr = vstr_new();
     o->pos = 0;
     return o;
 }
 
-STATIC mp_obj_t stringio_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t stringio_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     (void)n_kw; // TODO check n_kw==0
     mp_obj_stringio_t *o = stringio_new(type_in);
 
diff --git a/py/objtuple.c b/py/objtuple.c
index 86720ed..c21390a 100644
--- a/py/objtuple.c
+++ b/py/objtuple.c
@@ -61,7 +61,7 @@
     }
 }
 
-STATIC mp_obj_t mp_obj_tuple_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t mp_obj_tuple_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     (void)type_in;
 
     mp_arg_check_num(n_args, n_kw, 0, 1, false);
diff --git a/py/objtype.c b/py/objtype.c
index c9ab596..39998c5 100644
--- a/py/objtype.c
+++ b/py/objtype.c
@@ -43,14 +43,14 @@
 #define DEBUG_printf(...) (void)0
 #endif
 
-STATIC mp_obj_t static_class_method_make_new(mp_obj_t self_in, size_t n_args, size_t n_kw, const mp_obj_t *args);
+STATIC mp_obj_t static_class_method_make_new(const mp_obj_type_t *self_in, size_t n_args, size_t n_kw, const mp_obj_t *args);
 
 /******************************************************************************/
 // instance object
 
-STATIC mp_obj_t mp_obj_new_instance(mp_obj_t class, uint subobjs) {
+STATIC mp_obj_t mp_obj_new_instance(const mp_obj_type_t *class, uint subobjs) {
     mp_obj_instance_t *o = m_new_obj_var(mp_obj_instance_t, mp_obj_t, subobjs);
-    o->base.type = MP_OBJ_TO_PTR(class);
+    o->base.type = class;
     mp_map_init(&o->members, 0);
     mp_seq_clear(o->subobj, 0, subobjs, sizeof(*o->subobj));
     return MP_OBJ_FROM_PTR(o);
@@ -235,16 +235,14 @@
     mp_printf(print, "<%s object at %p>", mp_obj_get_type_str(self_in), self_in);
 }
 
-mp_obj_t mp_obj_instance_make_new(mp_obj_t self_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
-    assert(MP_OBJ_IS_TYPE(self_in, &mp_type_type));
-    mp_obj_type_t *self = MP_OBJ_TO_PTR(self_in);
+mp_obj_t mp_obj_instance_make_new(const mp_obj_type_t *self, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     assert(mp_obj_is_instance_type(self));
 
     const mp_obj_type_t *native_base;
     uint num_native_bases = instance_count_native_bases(self, &native_base);
     assert(num_native_bases < 2);
 
-    mp_obj_instance_t *o = MP_OBJ_TO_PTR(mp_obj_new_instance(self_in, num_native_bases));
+    mp_obj_instance_t *o = MP_OBJ_TO_PTR(mp_obj_new_instance(self, num_native_bases));
 
     // This executes only "__new__" part of obejection creation.
     // TODO: This won't work will for classes with native bases.
@@ -269,14 +267,15 @@
     if (init_fn[0] == MP_OBJ_SENTINEL) {
         // Native type's constructor is what wins - it gets all our arguments,
         // and none Python classes are initialized at all.
-        o->subobj[0] = native_base->make_new(MP_OBJ_FROM_PTR(native_base), n_args, n_kw, args);
+        o->subobj[0] = native_base->make_new(native_base, n_args, n_kw, args);
     } else if (init_fn[0] != MP_OBJ_NULL) {
         // now call Python class __new__ function with all args
         if (n_args == 0 && n_kw == 0) {
-            new_ret = mp_call_function_n_kw(init_fn[0], 1, 0, (mp_obj_t*)(void*)&self_in);
+            mp_obj_t args2[1] = {MP_OBJ_FROM_PTR(self)};
+            new_ret = mp_call_function_n_kw(init_fn[0], 1, 0, args2);
         } else {
             mp_obj_t *args2 = m_new(mp_obj_t, 1 + n_args + 2 * n_kw);
-            args2[0] = self_in;
+            args2[0] = MP_OBJ_FROM_PTR(self);
             memcpy(args2 + 1, args, (n_args + 2 * n_kw) * sizeof(mp_obj_t));
             new_ret = mp_call_function_n_kw(init_fn[0], n_args + 1, n_kw, args2);
             m_del(mp_obj_t, args2, 1 + n_args + 2 * n_kw);
@@ -778,7 +777,7 @@
     mp_printf(print, "<class '%q'>", self->name);
 }
 
-STATIC mp_obj_t type_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t type_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     (void)type_in;
 
     mp_arg_check_num(n_args, n_kw, 1, 3, false);
@@ -813,7 +812,7 @@
     }
 
     // make new instance
-    mp_obj_t o = self->make_new(self_in, n_args, n_kw, args);
+    mp_obj_t o = self->make_new(self, n_args, n_kw, args);
 
     // return new instance
     return o;
@@ -931,7 +930,7 @@
         // __new__ slot exists; check if it is a function
         if (MP_OBJ_IS_FUN(elem->value)) {
             // __new__ is a function, wrap it in a staticmethod decorator
-            elem->value = static_class_method_make_new(MP_OBJ_FROM_PTR(&mp_type_staticmethod), 1, 0, &elem->value);
+            elem->value = static_class_method_make_new(&mp_type_staticmethod, 1, 0, &elem->value);
         }
     }
 
@@ -957,7 +956,7 @@
     mp_print_str(print, ">");
 }
 
-STATIC mp_obj_t super_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t super_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     (void)type_in;
     // 0 arguments are turned into 2 in the compiler
     // 1 argument is not yet implemented
@@ -1108,8 +1107,7 @@
 /******************************************************************************/
 // staticmethod and classmethod types (probably should go in a different file)
 
-STATIC mp_obj_t static_class_method_make_new(mp_obj_t self_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
-    mp_obj_type_t *self = MP_OBJ_TO_PTR(self_in);
+STATIC mp_obj_t static_class_method_make_new(const mp_obj_type_t *self, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     assert(self == &mp_type_staticmethod || self == &mp_type_classmethod);
 
     mp_arg_check_num(n_args, n_kw, 1, 1, false);
diff --git a/py/objtype.h b/py/objtype.h
index 06227cf..61efd00 100644
--- a/py/objtype.h
+++ b/py/objtype.h
@@ -47,6 +47,6 @@
 #define mp_obj_is_instance_type(type) ((type)->make_new == mp_obj_instance_make_new)
 #define mp_obj_is_native_type(type) ((type)->make_new != mp_obj_instance_make_new)
 // this needs to be exposed for the above macros to work correctly
-mp_obj_t mp_obj_instance_make_new(mp_obj_t self_in, size_t n_args, size_t n_kw, const mp_obj_t *args);
+mp_obj_t mp_obj_instance_make_new(const mp_obj_type_t *self_in, size_t n_args, size_t n_kw, const mp_obj_t *args);
 
 #endif // __MICROPY_INCLUDED_PY_OBJTYPE_H__
diff --git a/py/objzip.c b/py/objzip.c
index 4b240fb..d4cd614 100644
--- a/py/objzip.c
+++ b/py/objzip.c
@@ -36,11 +36,11 @@
     mp_obj_t iters[];
 } mp_obj_zip_t;
 
-STATIC mp_obj_t zip_make_new(mp_obj_t type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+STATIC mp_obj_t zip_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     mp_arg_check_num(n_args, n_kw, 0, MP_OBJ_FUN_ARGS_MAX, false);
 
     mp_obj_zip_t *o = m_new_obj_var(mp_obj_zip_t, mp_obj_t, n_args);
-    o->base.type = MP_OBJ_TO_PTR(type_in);
+    o->base.type = type;
     o->n_iters = n_args;
     for (mp_uint_t i = 0; i < n_args; i++) {
         o->iters[i] = mp_getiter(args[i]);