diff --git a/py/obj.h b/py/obj.h
index 7ba4c0a5f2..598d6508da 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -394,19 +394,21 @@ typedef struct _mp_rom_obj_t { mp_const_obj_t o; } mp_rom_obj_t;
         .table = (mp_map_elem_t *)(mp_rom_map_elem_t *)table_name, \
     }
 
-#define MP_DEFINE_CONST_DICT(dict_name, table_name) \
+#define MP_DEFINE_CONST_DICT_WITH_SIZE(dict_name, table_name, n) \
     const mp_obj_dict_t dict_name = { \
         .base = {&mp_type_dict}, \
         .map = { \
             .all_keys_are_qstrs = 1, \
             .is_fixed = 1, \
             .is_ordered = 1, \
-            .used = MP_ARRAY_SIZE(table_name), \
-            .alloc = MP_ARRAY_SIZE(table_name), \
+            .used = n, \
+            .alloc = n, \
             .table = (mp_map_elem_t *)(mp_rom_map_elem_t *)table_name, \
         }, \
     }
 
+#define MP_DEFINE_CONST_DICT(dict_name, table_name) MP_DEFINE_CONST_DICT_WITH_SIZE(dict_name, table_name, MP_ARRAY_SIZE(table_name))
+
 // These macros are used to declare and define constant staticmethond and classmethod objects
 // You can put "static" in front of the definitions to make them local
 
@@ -789,7 +791,7 @@ mp_obj_t mp_obj_new_str(const char *data, size_t len);
 mp_obj_t mp_obj_new_str_via_qstr(const char *data, size_t len);
 mp_obj_t mp_obj_new_str_from_vstr(const mp_obj_type_t *type, vstr_t *vstr);
 mp_obj_t mp_obj_new_bytes(const byte *data, size_t len);
-mp_obj_t mp_obj_new_bytearray(size_t n, void *items);
+mp_obj_t mp_obj_new_bytearray(size_t n, const void *items);
 mp_obj_t mp_obj_new_bytearray_by_ref(size_t n, void *items);
 #if MICROPY_PY_BUILTINS_FLOAT
 mp_obj_t mp_obj_new_int_from_float(mp_float_t val);
diff --git a/py/objarray.c b/py/objarray.c
index bff3126a2b..11bd7bb15c 100644
--- a/py/objarray.c
+++ b/py/objarray.c
@@ -381,7 +381,7 @@ STATIC mp_obj_t array_append(mp_obj_t self_in, mp_obj_t arg) {
     self->free--;
     return mp_const_none; // return None, as per CPython
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_2(array_append_obj, array_append);
+MP_DEFINE_CONST_FUN_OBJ_2(mp_obj_array_append_obj, array_append);
 
 STATIC mp_obj_t array_extend(mp_obj_t self_in, mp_obj_t arg_in) {
     // self is not a memoryview, so we don't need to use (& TYPECODE_MASK)
@@ -413,7 +413,7 @@ STATIC mp_obj_t array_extend(mp_obj_t self_in, mp_obj_t arg_in) {
 
     return mp_const_none;
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_2(array_extend_obj, array_extend);
+MP_DEFINE_CONST_FUN_OBJ_2(mp_obj_array_extend_obj, array_extend);
 #endif
 
 STATIC mp_obj_t array_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t value) {
@@ -564,18 +564,6 @@ STATIC mp_int_t array_get_buffer(mp_obj_t o_in, mp_buffer_info_t *bufinfo, mp_ui
     return 0;
 }
 
-#if MICROPY_PY_BUILTINS_BYTEARRAY || MICROPY_PY_ARRAY
-STATIC const mp_rom_map_elem_t array_locals_dict_table[] = {
-    { MP_ROM_QSTR(MP_QSTR_append), MP_ROM_PTR(&array_append_obj) },
-    { MP_ROM_QSTR(MP_QSTR_extend), MP_ROM_PTR(&array_extend_obj) },
-    #if MICROPY_CPYTHON_COMPAT
-    { MP_ROM_QSTR(MP_QSTR_decode), MP_ROM_PTR(&bytes_decode_obj) },
-    #endif
-};
-
-STATIC MP_DEFINE_CONST_DICT(array_locals_dict, array_locals_dict_table);
-#endif
-
 #if MICROPY_PY_ARRAY
 const mp_obj_type_t mp_type_array = {
     { &mp_type_type },
@@ -587,7 +575,7 @@ const mp_obj_type_t mp_type_array = {
     .binary_op = array_binary_op,
     .subscr = array_subscr,
     .buffer_p = { .get_buffer = array_get_buffer },
-    .locals_dict = (mp_obj_dict_t *)&array_locals_dict,
+    .locals_dict = (mp_obj_dict_t *)&mp_obj_array_locals_dict,
 };
 #endif
 
@@ -603,7 +591,7 @@ const mp_obj_type_t mp_type_bytearray = {
     .binary_op = array_binary_op,
     .subscr = array_subscr,
     .buffer_p = { .get_buffer = array_get_buffer },
-    .locals_dict = (mp_obj_dict_t *)&array_locals_dict,
+    .locals_dict = (mp_obj_dict_t *)&mp_obj_bytearray_locals_dict,
 };
 #endif
 
@@ -631,7 +619,7 @@ size_t mp_obj_array_len(mp_obj_t self_in) {
 */
 
 #if MICROPY_PY_BUILTINS_BYTEARRAY
-mp_obj_t mp_obj_new_bytearray(size_t n, void *items) {
+mp_obj_t mp_obj_new_bytearray(size_t n, const void *items) {
     mp_obj_array_t *o = array_new(BYTEARRAY_TYPECODE, n);
     memcpy(o->items, items, n);
     return MP_OBJ_FROM_PTR(o);
diff --git a/py/objarray.h b/py/objarray.h
index 94c31c9693..48a26c3fb3 100644
--- a/py/objarray.h
+++ b/py/objarray.h
@@ -59,4 +59,9 @@ static inline void mp_obj_memoryview_init(mp_obj_array_t *self, size_t typecode,
 }
 #endif
 
+#if MICROPY_PY_ARRAY || MICROPY_PY_BUILTINS_BYTEARRAY
+MP_DECLARE_CONST_FUN_OBJ_2(mp_obj_array_append_obj);
+MP_DECLARE_CONST_FUN_OBJ_2(mp_obj_array_extend_obj);
+#endif
+
 #endif // MICROPY_INCLUDED_PY_OBJARRAY_H
diff --git a/py/objstr.c b/py/objstr.c
index f15a2d9744..162229c62b 100644
--- a/py/objstr.c
+++ b/py/objstr.c
@@ -41,6 +41,26 @@ STATIC mp_obj_t str_modulo_format(mp_obj_t pattern, size_t n_args, const mp_obj_
 STATIC mp_obj_t mp_obj_new_bytes_iterator(mp_obj_t str, mp_obj_iter_buf_t *iter_buf);
 STATIC NORETURN void bad_implicit_conversion(mp_obj_t self_in);
 
+STATIC void str_check_arg_type(const mp_obj_type_t *self_type, const mp_obj_t arg) {
+    // String operations generally need the args type to match the object they're called on,
+    // e.g. str.find(str), byte.startswith(byte)
+    // with the exception that bytes may be used for bytearray and vice versa.
+    const mp_obj_type_t *arg_type = mp_obj_get_type(arg);
+
+    #if MICROPY_PY_BUILTINS_BYTEARRAY
+    if (arg_type == &mp_type_bytearray) {
+        arg_type = &mp_type_bytes;
+    }
+    if (self_type == &mp_type_bytearray) {
+        self_type = &mp_type_bytes;
+    }
+    #endif
+
+    if (arg_type != self_type) {
+        bad_implicit_conversion(arg);
+    }
+}
+
 /******************************************************************************/
 /* str                                                                        */
 
@@ -452,6 +472,7 @@ STATIC mp_obj_t bytes_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
 STATIC mp_obj_t str_join(mp_obj_t self_in, mp_obj_t arg) {
     mp_check_self(mp_obj_is_str_or_bytes(self_in));
     const mp_obj_type_t *self_type = mp_obj_get_type(self_in);
+    const mp_obj_type_t *ret_type = self_type;
 
     // get separation string
     GET_STR_DATA_LEN(self_in, sep_str, sep_len);
@@ -469,8 +490,19 @@ STATIC mp_obj_t str_join(mp_obj_t self_in, mp_obj_t arg) {
 
     // count required length
     size_t required_len = 0;
+    #if MICROPY_PY_BUILTINS_BYTEARRAY
+    if (self_type == &mp_type_bytearray) {
+        self_type = &mp_type_bytes;
+    }
+    #endif
     for (size_t i = 0; i < seq_len; i++) {
-        if (mp_obj_get_type(seq_items[i]) != self_type) {
+        const mp_obj_type_t *seq_type = mp_obj_get_type(seq_items[i]);
+        #if MICROPY_PY_BUILTINS_BYTEARRAY
+        if (seq_type == &mp_type_bytearray) {
+            seq_type = &mp_type_bytes;
+        }
+        #endif
+        if (seq_type != self_type) {
             mp_raise_TypeError(
                 MP_ERROR_TEXT("join expects a list of str/bytes objects consistent with self object"));
         }
@@ -496,7 +528,7 @@ STATIC mp_obj_t str_join(mp_obj_t self_in, mp_obj_t arg) {
     }
 
     // return joined string
-    return mp_obj_new_str_from_vstr(self_type, &vstr);
+    return mp_obj_new_str_from_vstr(ret_type, &vstr);
 }
 MP_DEFINE_CONST_FUN_OBJ_2(str_join_obj, str_join);
 
@@ -545,9 +577,7 @@ mp_obj_t mp_obj_str_split(size_t n_args, const mp_obj_t *args) {
 
     } else {
         // sep given
-        if (mp_obj_get_type(sep) != self_type) {
-            bad_implicit_conversion(sep);
-        }
+        str_check_arg_type(self_type, sep);
 
         size_t sep_len;
         const char *sep_str = mp_obj_str_get_data(sep, &sep_len);
@@ -699,9 +729,7 @@ STATIC mp_obj_t str_finder(size_t n_args, const mp_obj_t *args, int direction, b
     mp_check_self(mp_obj_is_str_or_bytes(args[0]));
 
     // check argument type
-    if (mp_obj_get_type(args[1]) != self_type) {
-        bad_implicit_conversion(args[1]);
-    }
+    str_check_arg_type(self_type, args[1]);
 
     GET_STR_DATA_LEN(args[0], haystack, haystack_len);
     GET_STR_DATA_LEN(args[1], needle, needle_len);
@@ -805,9 +833,7 @@ STATIC mp_obj_t str_uni_strip(int type, size_t n_args, const mp_obj_t *args) {
         chars_to_del = whitespace;
         chars_to_del_len = sizeof(whitespace) - 1;
     } else {
-        if (mp_obj_get_type(args[1]) != self_type) {
-            bad_implicit_conversion(args[1]);
-        }
+        str_check_arg_type(self_type, args[1]);
         GET_STR_DATA_LEN(args[1], s, l);
         chars_to_del = s;
         chars_to_del_len = l;
@@ -1633,13 +1659,8 @@ STATIC mp_obj_t str_replace(size_t n_args, const mp_obj_t *args) {
 
     const mp_obj_type_t *self_type = mp_obj_get_type(args[0]);
 
-    if (mp_obj_get_type(args[1]) != self_type) {
-        bad_implicit_conversion(args[1]);
-    }
-
-    if (mp_obj_get_type(args[2]) != self_type) {
-        bad_implicit_conversion(args[2]);
-    }
+    str_check_arg_type(self_type, args[1]);
+    str_check_arg_type(self_type, args[2]);
 
     // extract string data
 
@@ -1726,9 +1747,7 @@ STATIC mp_obj_t str_count(size_t n_args, const mp_obj_t *args) {
     mp_check_self(mp_obj_is_str_or_bytes(args[0]));
 
     // check argument type
-    if (mp_obj_get_type(args[1]) != self_type) {
-        bad_implicit_conversion(args[1]);
-    }
+    str_check_arg_type(self_type, args[1]);
 
     GET_STR_DATA_LEN(args[0], haystack, haystack_len);
     GET_STR_DATA_LEN(args[1], needle, needle_len);
@@ -1767,9 +1786,7 @@ MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(str_count_obj, 2, 4, str_count);
 STATIC mp_obj_t str_partitioner(mp_obj_t self_in, mp_obj_t arg, int direction) {
     mp_check_self(mp_obj_is_str_or_bytes(self_in));
     const mp_obj_type_t *self_type = mp_obj_get_type(self_in);
-    if (self_type != mp_obj_get_type(arg)) {
-        bad_implicit_conversion(arg);
-    }
+    str_check_arg_type(self_type, arg);
 
     GET_STR_DATA_LEN(self_in, str, str_len);
     GET_STR_DATA_LEN(arg, sep, sep_len);
@@ -1795,6 +1812,12 @@ STATIC mp_obj_t str_partitioner(mp_obj_t self_in, mp_obj_t arg, int direction) {
         result[2] = self_in;
     }
 
+    #if MICROPY_PY_BUILTINS_BYTEARRAY
+    if (mp_obj_get_type(arg) != self_type) {
+        arg = mp_obj_new_str_of_type(self_type, sep, sep_len);
+    }
+    #endif
+
     const byte *position_ptr = find_subbytes(str, str_len, sep, sep_len, direction);
     if (position_ptr != NULL) {
         size_t position = position_ptr - str;
@@ -1940,17 +1963,15 @@ mp_int_t mp_obj_str_get_buffer(mp_obj_t self_in, mp_buffer_info_t *bufinfo, mp_u
     }
 }
 
-STATIC const mp_rom_map_elem_t str8_locals_dict_table[] = {
+// This locals table is used for the following types: str, bytes, bytearray, array.array.
+// Each type takes a different section (start to end offset) of this table.
+STATIC const mp_rom_map_elem_t array_bytearray_str_bytes_locals_table[] = {
+    #if MICROPY_PY_ARRAY || MICROPY_PY_BUILTINS_BYTEARRAY
+    { MP_ROM_QSTR(MP_QSTR_append), MP_ROM_PTR(&mp_obj_array_append_obj) },
+    { MP_ROM_QSTR(MP_QSTR_extend), MP_ROM_PTR(&mp_obj_array_extend_obj) },
+    #endif
     #if MICROPY_CPYTHON_COMPAT
     { MP_ROM_QSTR(MP_QSTR_decode), MP_ROM_PTR(&bytes_decode_obj) },
-    #if !MICROPY_PY_BUILTINS_STR_UNICODE
-    // If we have separate unicode type, then here we have methods only
-    // for bytes type, and it should not have encode() methods. Otherwise,
-    // we have non-compliant-but-practical bytestring type, which shares
-    // method table with bytes, so they both have encode() and decode()
-    // methods (which should do type checking at runtime).
-    { MP_ROM_QSTR(MP_QSTR_encode), MP_ROM_PTR(&str_encode_obj) },
-    #endif
     #endif
     { MP_ROM_QSTR(MP_QSTR_find), MP_ROM_PTR(&str_find_obj) },
     { MP_ROM_QSTR(MP_QSTR_rfind), MP_ROM_PTR(&str_rfind_obj) },
@@ -1986,9 +2007,46 @@ STATIC const mp_rom_map_elem_t str8_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_isdigit), MP_ROM_PTR(&str_isdigit_obj) },
     { MP_ROM_QSTR(MP_QSTR_isupper), MP_ROM_PTR(&str_isupper_obj) },
     { MP_ROM_QSTR(MP_QSTR_islower), MP_ROM_PTR(&str_islower_obj) },
+    #if MICROPY_CPYTHON_COMPAT
+    { MP_ROM_QSTR(MP_QSTR_encode), MP_ROM_PTR(&str_encode_obj) },
+    #endif
 };
 
-STATIC MP_DEFINE_CONST_DICT(str8_locals_dict, str8_locals_dict_table);
+#if MICROPY_CPYTHON_COMPAT
+#define TABLE_ENTRIES_COMPAT 1
+#else
+#define TABLE_ENTRIES_COMPAT 0
+#endif
+
+#if MICROPY_PY_ARRAY || MICROPY_PY_BUILTINS_BYTEARRAY
+#define TABLE_ENTRIES_ARRAY 2
+#else
+#define TABLE_ENTRIES_ARRAY 0
+#endif
+
+MP_DEFINE_CONST_DICT_WITH_SIZE(mp_obj_str_locals_dict,
+    array_bytearray_str_bytes_locals_table + TABLE_ENTRIES_ARRAY + TABLE_ENTRIES_COMPAT,
+    MP_ARRAY_SIZE(array_bytearray_str_bytes_locals_table) - (TABLE_ENTRIES_ARRAY + TABLE_ENTRIES_COMPAT));
+
+#if TABLE_ENTRIES_COMPAT == 0
+#define mp_obj_bytes_locals_dict mp_obj_str_locals_dict
+#else
+MP_DEFINE_CONST_DICT_WITH_SIZE(mp_obj_bytes_locals_dict,
+    array_bytearray_str_bytes_locals_table + TABLE_ENTRIES_ARRAY,
+    MP_ARRAY_SIZE(array_bytearray_str_bytes_locals_table) - (TABLE_ENTRIES_ARRAY + TABLE_ENTRIES_COMPAT));
+#endif
+
+#if MICROPY_PY_BUILTINS_BYTEARRAY
+MP_DEFINE_CONST_DICT_WITH_SIZE(mp_obj_bytearray_locals_dict,
+    array_bytearray_str_bytes_locals_table,
+    MP_ARRAY_SIZE(array_bytearray_str_bytes_locals_table) - TABLE_ENTRIES_COMPAT);
+#endif
+
+#if MICROPY_PY_ARRAY
+MP_DEFINE_CONST_DICT_WITH_SIZE(mp_obj_array_locals_dict,
+    array_bytearray_str_bytes_locals_table,
+    TABLE_ENTRIES_ARRAY);
+#endif
 
 #if !MICROPY_PY_BUILTINS_STR_UNICODE
 STATIC mp_obj_t mp_obj_new_str_iterator(mp_obj_t str, mp_obj_iter_buf_t *iter_buf);
@@ -2002,9 +2060,9 @@ const mp_obj_type_t mp_type_str = {
     .subscr = bytes_subscr,
     .getiter = mp_obj_new_str_iterator,
     .buffer_p = { .get_buffer = mp_obj_str_get_buffer },
-    .locals_dict = (mp_obj_dict_t *)&str8_locals_dict,
+    .locals_dict = (mp_obj_dict_t *)&mp_obj_str_locals_dict,
 };
-#endif
+#endif // !MICROPY_PY_BUILTINS_STR_UNICODE
 
 // Reuses most of methods from str
 const mp_obj_type_t mp_type_bytes = {
@@ -2016,7 +2074,7 @@ const mp_obj_type_t mp_type_bytes = {
     .subscr = bytes_subscr,
     .getiter = mp_obj_new_bytes_iterator,
     .buffer_p = { .get_buffer = mp_obj_str_get_buffer },
-    .locals_dict = (mp_obj_dict_t *)&str8_locals_dict,
+    .locals_dict = (mp_obj_dict_t *)&mp_obj_bytes_locals_dict,
 };
 
 // The zero-length bytes object, with data that includes a null-terminating byte
@@ -2044,6 +2102,10 @@ mp_obj_t mp_obj_new_str_copy(const mp_obj_type_t *type, const byte *data, size_t
 mp_obj_t mp_obj_new_str_of_type(const mp_obj_type_t *type, const byte *data, size_t len) {
     if (type == &mp_type_str) {
         return mp_obj_new_str((const char *)data, len);
+    #if MICROPY_PY_BUILTINS_BYTEARRAY
+    } else if (type == &mp_type_bytearray) {
+        return mp_obj_new_bytearray(len, data);
+    #endif
     } else {
         return mp_obj_new_bytes(data, len);
     }
@@ -2068,18 +2130,24 @@ mp_obj_t mp_obj_new_str_from_vstr(const mp_obj_type_t *type, vstr_t *vstr) {
         }
     }
 
-    // make a new str/bytes object
-    mp_obj_str_t *o = mp_obj_malloc(mp_obj_str_t, type);
-    o->len = vstr->len;
-    o->hash = qstr_compute_hash((byte *)vstr->buf, vstr->len);
+    byte *data;
     if (vstr->len + 1 == vstr->alloc) {
-        o->data = (byte *)vstr->buf;
+        data = (byte *)vstr->buf;
     } else {
-        o->data = (byte *)m_renew(char, vstr->buf, vstr->alloc, vstr->len + 1);
+        data = (byte *)m_renew(char, vstr->buf, vstr->alloc, vstr->len + 1);
     }
-    ((byte *)o->data)[o->len] = '\0'; // add null byte
+    data[vstr->len] = '\0'; // add null byte
     vstr->buf = NULL;
     vstr->alloc = 0;
+    #if MICROPY_PY_BUILTINS_BYTEARRAY
+    if (type == &mp_type_bytearray) {
+        return mp_obj_new_bytearray_by_ref(vstr->len, data);
+    }
+    #endif
+    mp_obj_str_t *o = mp_obj_malloc(mp_obj_str_t, type);
+    o->len = vstr->len;
+    o->hash = qstr_compute_hash(data, vstr->len);
+    o->data = data;
     return MP_OBJ_FROM_PTR(o);
 }
 
@@ -2179,6 +2247,7 @@ const byte *mp_obj_str_get_data_no_check(mp_obj_t self_in, size_t *len) {
     if (mp_obj_is_qstr(self_in)) {
         return qstr_data(MP_OBJ_QSTR_VALUE(self_in), len);
     } else {
+        MP_STATIC_ASSERT_STR_ARRAY_COMPATIBLE;
         *len = ((mp_obj_str_t *)MP_OBJ_TO_PTR(self_in))->len;
         return ((mp_obj_str_t *)MP_OBJ_TO_PTR(self_in))->data;
     }
diff --git a/py/objstr.h b/py/objstr.h
index 92b065d869..7d86ec30ba 100644
--- a/py/objstr.h
+++ b/py/objstr.h
@@ -27,6 +27,7 @@
 #define MICROPY_INCLUDED_PY_OBJSTR_H
 
 #include "py/obj.h"
+#include "py/objarray.h"
 
 typedef struct _mp_obj_str_t {
     mp_obj_base_t base;
@@ -36,6 +37,13 @@ typedef struct _mp_obj_str_t {
     const byte *data;
 } mp_obj_str_t;
 
+// This static assert is used to ensure that mp_obj_str_t and mp_obj_array_t are compatible,
+// meaning that their len and data/items entries are at the same offsets in the struct.
+// This allows the same code to be used for str/bytes and bytearray.
+#define MP_STATIC_ASSERT_STR_ARRAY_COMPATIBLE \
+    MP_STATIC_ASSERT(offsetof(mp_obj_str_t, len) == offsetof(mp_obj_array_t, len) \
+    && offsetof(mp_obj_str_t, data) == offsetof(mp_obj_array_t, items))
+
 #define MP_DEFINE_STR_OBJ(obj_name, str) mp_obj_str_t obj_name = {{&mp_type_str}, 0, sizeof(str) - 1, (const byte *)str}
 
 // use this macro to extract the string hash
@@ -70,6 +78,7 @@ const byte *mp_obj_str_get_data_no_check(mp_obj_t self_in, size_t *len);
     if (mp_obj_is_qstr(str_obj_in)) { \
         str_data = qstr_data(MP_OBJ_QSTR_VALUE(str_obj_in), &str_len); \
     } else { \
+        MP_STATIC_ASSERT_STR_ARRAY_COMPATIBLE; \
         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; \
     }
@@ -118,4 +127,14 @@ MP_DECLARE_CONST_FUN_OBJ_1(str_isupper_obj);
 MP_DECLARE_CONST_FUN_OBJ_1(str_islower_obj);
 MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(bytes_decode_obj);
 
+extern const mp_obj_dict_t mp_obj_str_locals_dict;
+
+#if MICROPY_PY_BUILTINS_BYTEARRAY
+extern const mp_obj_dict_t mp_obj_bytearray_locals_dict;
+#endif
+
+#if MICROPY_PY_ARRAY
+extern const mp_obj_dict_t mp_obj_array_locals_dict;
+#endif
+
 #endif // MICROPY_INCLUDED_PY_OBJSTR_H
diff --git a/py/objstrunicode.c b/py/objstrunicode.c
index ed79ad68a9..d36dd8b137 100644
--- a/py/objstrunicode.c
+++ b/py/objstrunicode.c
@@ -116,7 +116,11 @@ const byte *str_index_to_ptr(const mp_obj_type_t *type, const byte *self_data, s
     mp_obj_t index, bool is_slice) {
     // All str functions also handle bytes objects, and they call str_index_to_ptr(),
     // so it must handle bytes.
-    if (type == &mp_type_bytes) {
+    if (type == &mp_type_bytes
+        #if MICROPY_PY_BUILTINS_BYTEARRAY
+        || type == &mp_type_bytearray
+        #endif
+        ) {
         // Taken from objstr.c:str_index_to_ptr()
         size_t index_val = mp_get_index(type, self_len, index, is_slice);
         return self_data + index_val;
@@ -225,48 +229,6 @@ STATIC mp_obj_t str_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
     }
 }
 
-STATIC const mp_rom_map_elem_t struni_locals_dict_table[] = {
-    #if MICROPY_CPYTHON_COMPAT
-    { MP_ROM_QSTR(MP_QSTR_encode), MP_ROM_PTR(&str_encode_obj) },
-    #endif
-    { MP_ROM_QSTR(MP_QSTR_find), MP_ROM_PTR(&str_find_obj) },
-    { MP_ROM_QSTR(MP_QSTR_rfind), MP_ROM_PTR(&str_rfind_obj) },
-    { MP_ROM_QSTR(MP_QSTR_index), MP_ROM_PTR(&str_index_obj) },
-    { MP_ROM_QSTR(MP_QSTR_rindex), MP_ROM_PTR(&str_rindex_obj) },
-    { MP_ROM_QSTR(MP_QSTR_join), MP_ROM_PTR(&str_join_obj) },
-    { MP_ROM_QSTR(MP_QSTR_split), MP_ROM_PTR(&str_split_obj) },
-    #if MICROPY_PY_BUILTINS_STR_SPLITLINES
-    { MP_ROM_QSTR(MP_QSTR_splitlines), MP_ROM_PTR(&str_splitlines_obj) },
-    #endif
-    { MP_ROM_QSTR(MP_QSTR_rsplit), MP_ROM_PTR(&str_rsplit_obj) },
-    { MP_ROM_QSTR(MP_QSTR_startswith), MP_ROM_PTR(&str_startswith_obj) },
-    { MP_ROM_QSTR(MP_QSTR_endswith), MP_ROM_PTR(&str_endswith_obj) },
-    { MP_ROM_QSTR(MP_QSTR_strip), MP_ROM_PTR(&str_strip_obj) },
-    { MP_ROM_QSTR(MP_QSTR_lstrip), MP_ROM_PTR(&str_lstrip_obj) },
-    { MP_ROM_QSTR(MP_QSTR_rstrip), MP_ROM_PTR(&str_rstrip_obj) },
-    { MP_ROM_QSTR(MP_QSTR_format), MP_ROM_PTR(&str_format_obj) },
-    { MP_ROM_QSTR(MP_QSTR_replace), MP_ROM_PTR(&str_replace_obj) },
-    #if MICROPY_PY_BUILTINS_STR_COUNT
-    { MP_ROM_QSTR(MP_QSTR_count), MP_ROM_PTR(&str_count_obj) },
-    #endif
-    #if MICROPY_PY_BUILTINS_STR_PARTITION
-    { MP_ROM_QSTR(MP_QSTR_partition), MP_ROM_PTR(&str_partition_obj) },
-    { MP_ROM_QSTR(MP_QSTR_rpartition), MP_ROM_PTR(&str_rpartition_obj) },
-    #endif
-    #if MICROPY_PY_BUILTINS_STR_CENTER
-    { MP_ROM_QSTR(MP_QSTR_center), MP_ROM_PTR(&str_center_obj) },
-    #endif
-    { MP_ROM_QSTR(MP_QSTR_lower), MP_ROM_PTR(&str_lower_obj) },
-    { MP_ROM_QSTR(MP_QSTR_upper), MP_ROM_PTR(&str_upper_obj) },
-    { MP_ROM_QSTR(MP_QSTR_isspace), MP_ROM_PTR(&str_isspace_obj) },
-    { MP_ROM_QSTR(MP_QSTR_isalpha), MP_ROM_PTR(&str_isalpha_obj) },
-    { MP_ROM_QSTR(MP_QSTR_isdigit), MP_ROM_PTR(&str_isdigit_obj) },
-    { MP_ROM_QSTR(MP_QSTR_isupper), MP_ROM_PTR(&str_isupper_obj) },
-    { MP_ROM_QSTR(MP_QSTR_islower), MP_ROM_PTR(&str_islower_obj) },
-};
-
-STATIC MP_DEFINE_CONST_DICT(struni_locals_dict, struni_locals_dict_table);
-
 const mp_obj_type_t mp_type_str = {
     { &mp_type_type },
     .name = MP_QSTR_str,
@@ -277,7 +239,7 @@ const mp_obj_type_t mp_type_str = {
     .subscr = str_subscr,
     .getiter = mp_obj_new_str_iterator,
     .buffer_p = { .get_buffer = mp_obj_str_get_buffer },
-    .locals_dict = (mp_obj_dict_t *)&struni_locals_dict,
+    .locals_dict = (mp_obj_dict_t *)&mp_obj_str_locals_dict,
 };
 
 /******************************************************************************/
diff --git a/tests/basics/bytearray_byte_operations.py b/tests/basics/bytearray_byte_operations.py
new file mode 100644
index 0000000000..7ce53cac53
--- /dev/null
+++ b/tests/basics/bytearray_byte_operations.py
@@ -0,0 +1,35 @@
+# test bytearray with its re-use of byte functions
+
+print(bytearray(b"hello world").find(b"ll"))
+print(bytearray(b"hello\x00world").rfind(b"l"))
+
+print(bytearray(b"abc  efg ").strip(b"g a"))
+print(bytearray(b"   spacious   ").lstrip())
+print(bytearray(b"www.example.com").lstrip(b"cmowz."))
+print(bytearray(b"   spacious   ").rstrip())
+print(bytearray(b"mississippi").rstrip(b"ipz"))
+
+print(bytearray(b"abc").split(b"a"))
+print(bytearray(b"abcabc").rsplit(b"bc"))
+
+print(bytearray(b"asdfasdf").replace(b"a", b"b"))
+
+print("00\x0000".index("0", 0))
+print("00\x0000".index("0", 3))
+print("00\x0000".rindex("0", 0))
+print("00\x0000".rindex("0", 3))
+
+print(bytearray(b"foobar").endswith(b"bar"))
+print(bytearray(b"1foo").startswith(b"foo", 1))
+
+print(bytearray(b" T E \x00 S T").lower())
+print(bytearray(b" te \x00 st").upper())
+
+print(bytearray(b" \t\n\r\v\f").isspace())
+print(bytearray(b"this ").isalpha())
+print(bytearray(b"0123456789").isdigit())
+print(bytearray(b"AB").isupper())
+print(bytearray(b"cheese-cake").islower())
+
+print(bytearray(b",").join((bytearray(b"abc"), bytearray(b"def"))))
+print(type(bytearray(b",").join((b"a", b"b", b"c"))))
diff --git a/tests/basics/bytearray_center.py b/tests/basics/bytearray_center.py
new file mode 100644
index 0000000000..c262a8c209
--- /dev/null
+++ b/tests/basics/bytearray_center.py
@@ -0,0 +1,8 @@
+try:
+    bytearray.center
+except AttributeError:
+    print("SKIP")
+    raise SystemExit
+
+print(bytearray(b"foo").center(6))
+print(type(bytearray(b"foo").center(6)))
diff --git a/tests/basics/bytearray_count.py b/tests/basics/bytearray_count.py
new file mode 100644
index 0000000000..a151c1e818
--- /dev/null
+++ b/tests/basics/bytearray_count.py
@@ -0,0 +1,7 @@
+try:
+    bytearray.count
+except AttributeError:
+    print("SKIP")
+    raise SystemExit
+
+print(bytearray(b"aaaa").count(b"a"))
diff --git a/tests/basics/bytearray_partition.py b/tests/basics/bytearray_partition.py
new file mode 100644
index 0000000000..b48ec4ed9b
--- /dev/null
+++ b/tests/basics/bytearray_partition.py
@@ -0,0 +1,8 @@
+try:
+    bytearray.partition
+except AttributeError:
+    print("SKIP")
+    raise SystemExit
+
+print(bytearray(b"asdsf").partition(b"s"))
+print(bytearray(b"asdsf").rpartition(b"s"))
diff --git a/tests/basics/bytes_center.py b/tests/basics/bytes_center.py
new file mode 100644
index 0000000000..5d8b41d92f
--- /dev/null
+++ b/tests/basics/bytes_center.py
@@ -0,0 +1,13 @@
+try:
+    bytes.center
+except:
+    print("SKIP")
+    raise SystemExit
+
+print(b"foo".center(0))
+print(b"foo".center(1))
+print(b"foo".center(3))
+print(b"foo".center(4))
+print(b"foo".center(5))
+print(b"foo".center(6))
+print(b"foo".center(20))