diff --git a/py/builtin.c b/py/builtin.c
index 6d3fc90..a8a7009 100644
--- a/py/builtin.c
+++ b/py/builtin.c
@@ -22,15 +22,15 @@
     assert(2 <= n_args);
 
     // we differ from CPython: we set the new __locals__ object here
-    mp_map_t *old_locals = rt_locals_get();
+    mp_map_t *old_locals = mp_locals_get();
     mp_obj_t class_locals = mp_obj_new_dict(0);
-    rt_locals_set(mp_obj_dict_get_map(class_locals));
+    mp_locals_set(mp_obj_dict_get_map(class_locals));
 
     // call the class code
-    mp_obj_t cell = rt_call_function_1(args[0], (mp_obj_t)0xdeadbeef);
+    mp_obj_t cell = mp_call_function_1(args[0], (mp_obj_t)0xdeadbeef);
 
     // restore old __locals__ object
-    rt_locals_set(old_locals);
+    mp_locals_set(old_locals);
 
     // get the class type (meta object) from the base objects
     mp_obj_t meta;
@@ -49,7 +49,7 @@
     meta_args[0] = args[1]; // class name
     meta_args[1] = mp_obj_new_tuple(n_args - 2, args + 2); // tuple of bases
     meta_args[2] = class_locals; // dict of members
-    mp_obj_t new_class = rt_call_function_n_kw(meta, 3, 0, meta_args);
+    mp_obj_t new_class = mp_call_function_n_kw(meta, 3, 0, meta_args);
 
     // store into cell if neede
     if (cell != mp_const_none) {
@@ -101,10 +101,10 @@
 MP_DEFINE_CONST_FUN_OBJ_1(mp_builtin_abs_obj, mp_builtin_abs);
 
 STATIC mp_obj_t mp_builtin_all(mp_obj_t o_in) {
-    mp_obj_t iterable = rt_getiter(o_in);
+    mp_obj_t iterable = mp_getiter(o_in);
     mp_obj_t item;
-    while ((item = rt_iternext(iterable)) != MP_OBJ_NULL) {
-        if (!rt_is_true(item)) {
+    while ((item = mp_iternext(iterable)) != MP_OBJ_NULL) {
+        if (!mp_obj_is_true(item)) {
             return mp_const_false;
         }
     }
@@ -114,10 +114,10 @@
 MP_DEFINE_CONST_FUN_OBJ_1(mp_builtin_all_obj, mp_builtin_all);
 
 STATIC mp_obj_t mp_builtin_any(mp_obj_t o_in) {
-    mp_obj_t iterable = rt_getiter(o_in);
+    mp_obj_t iterable = mp_getiter(o_in);
     mp_obj_t item;
-    while ((item = rt_iternext(iterable)) != MP_OBJ_NULL) {
-        if (rt_is_true(item)) {
+    while ((item = mp_iternext(iterable)) != MP_OBJ_NULL) {
+        if (mp_obj_is_true(item)) {
             return mp_const_true;
         }
     }
@@ -154,7 +154,7 @@
     mp_map_t *map = NULL;
     if (n_args == 0) {
         // make a list of names in the local name space
-        map = rt_locals_get();
+        map = mp_locals_get();
     } else { // n_args == 1
         // make a list of names in the given object
         if (MP_OBJ_IS_TYPE(args[0], &mp_type_module)) {
@@ -193,7 +193,7 @@
         mp_obj_t args[2];
         args[0] = MP_OBJ_NEW_SMALL_INT(i1 / i2);
         args[1] = MP_OBJ_NEW_SMALL_INT(i1 % i2);
-        return rt_build_tuple(2, args);
+        return mp_build_tuple(2, args);
     } else {
         nlr_jump(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "unsupported operand type(s) for divmod(): '%s' and '%s'", mp_obj_get_type_str(o1_in), mp_obj_get_type_str(o2_in)));
     }
@@ -209,7 +209,7 @@
 MP_DEFINE_CONST_FUN_OBJ_1(mp_builtin_hash_obj, mp_builtin_hash);
 
 STATIC mp_obj_t mp_builtin_iter(mp_obj_t o_in) {
-    return rt_getiter(o_in);
+    return mp_getiter(o_in);
 }
 
 MP_DEFINE_CONST_FUN_OBJ_1(mp_builtin_iter_obj, mp_builtin_iter);
@@ -228,10 +228,10 @@
 STATIC mp_obj_t mp_builtin_max(uint n_args, const mp_obj_t *args) {
     if (n_args == 1) {
         // given an iterable
-        mp_obj_t iterable = rt_getiter(args[0]);
+        mp_obj_t iterable = mp_getiter(args[0]);
         mp_obj_t max_obj = NULL;
         mp_obj_t item;
-        while ((item = rt_iternext(iterable)) != MP_OBJ_NULL) {
+        while ((item = mp_iternext(iterable)) != MP_OBJ_NULL) {
             if (max_obj == NULL || mp_obj_less(max_obj, item)) {
                 max_obj = item;
             }
@@ -257,10 +257,10 @@
 STATIC mp_obj_t mp_builtin_min(uint n_args, const mp_obj_t *args) {
     if (n_args == 1) {
         // given an iterable
-        mp_obj_t iterable = rt_getiter(args[0]);
+        mp_obj_t iterable = mp_getiter(args[0]);
         mp_obj_t min_obj = NULL;
         mp_obj_t item;
-        while ((item = rt_iternext(iterable)) != MP_OBJ_NULL) {
+        while ((item = mp_iternext(iterable)) != MP_OBJ_NULL) {
             if (min_obj == NULL || mp_obj_less(item, min_obj)) {
                 min_obj = item;
             }
@@ -284,7 +284,7 @@
 MP_DEFINE_CONST_FUN_OBJ_VAR(mp_builtin_min_obj, 1, mp_builtin_min);
 
 STATIC mp_obj_t mp_builtin_next(mp_obj_t o) {
-    mp_obj_t ret = rt_iternext_allow_raise(o);
+    mp_obj_t ret = mp_iternext_allow_raise(o);
     if (ret == MP_OBJ_NULL) {
         nlr_jump(mp_obj_new_exception(&mp_type_StopIteration));
     } else {
@@ -311,8 +311,8 @@
 STATIC mp_obj_t mp_builtin_pow(uint n_args, const mp_obj_t *args) {
     assert(2 <= n_args && n_args <= 3);
     switch (n_args) {
-        case 2: return rt_binary_op(RT_BINARY_OP_POWER, args[0], args[1]);
-        default: return rt_binary_op(RT_BINARY_OP_MODULO, rt_binary_op(RT_BINARY_OP_POWER, args[0], args[1]), args[2]); // TODO optimise...
+        case 2: return mp_binary_op(MP_BINARY_OP_POWER, args[0], args[1]);
+        default: return mp_binary_op(MP_BINARY_OP_MODULO, mp_binary_op(MP_BINARY_OP_POWER, args[0], args[1]), args[2]); // TODO optimise...
     }
 }
 
@@ -359,10 +359,10 @@
         case 1: value = mp_obj_new_int(0); break;
         default: value = args[1]; break;
     }
-    mp_obj_t iterable = rt_getiter(args[0]);
+    mp_obj_t iterable = mp_getiter(args[0]);
     mp_obj_t item;
-    while ((item = rt_iternext(iterable)) != MP_OBJ_NULL) {
-        value = rt_binary_op(RT_BINARY_OP_ADD, value, item);
+    while ((item = mp_iternext(iterable)) != MP_OBJ_NULL) {
+        value = mp_binary_op(MP_BINARY_OP_ADD, value, item);
     }
     return value;
 }
@@ -391,7 +391,7 @@
 
 STATIC mp_obj_t mp_builtin_getattr(mp_obj_t o_in, mp_obj_t attr) {
     assert(MP_OBJ_IS_QSTR(attr));
-    return rt_load_attr(o_in, MP_OBJ_QSTR_VALUE(attr));
+    return mp_load_attr(o_in, MP_OBJ_QSTR_VALUE(attr));
 }
 
 MP_DEFINE_CONST_FUN_OBJ_2(mp_builtin_getattr_obj, mp_builtin_getattr);