diff --git a/py/obj.c b/py/obj.c
index 6494a847a..e4bf7d7df 100644
--- a/py/obj.c
+++ b/py/obj.c
@@ -36,18 +36,18 @@
 #include "runtime0.h"
 #include "runtime.h"
 
-mp_obj_type_t *mp_obj_get_type(mp_obj_t o_in) {
+mp_obj_type_t *mp_obj_get_type(mp_const_obj_t o_in) {
     if (MP_OBJ_IS_SMALL_INT(o_in)) {
         return (mp_obj_t)&mp_type_int;
     } else if (MP_OBJ_IS_QSTR(o_in)) {
         return (mp_obj_t)&mp_type_str;
     } else {
-        mp_obj_base_t *o = o_in;
+        const mp_obj_base_t *o = o_in;
         return (mp_obj_t)o->type;
     }
 }
 
-const char *mp_obj_get_type_str(mp_obj_t o_in) {
+const char *mp_obj_get_type_str(mp_const_obj_t o_in) {
     return qstr_str(mp_obj_get_type(o_in)->name);
 }
 
diff --git a/py/obj.h b/py/obj.h
index 2418b2845..30a60b77d 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -398,9 +398,10 @@ mp_obj_t mp_obj_new_bound_meth(mp_obj_t meth, mp_obj_t self);
 mp_obj_t mp_obj_new_getitem_iter(mp_obj_t *args);
 mp_obj_t mp_obj_new_module(qstr module_name);
 
-mp_obj_type_t *mp_obj_get_type(mp_obj_t o_in);
-const char *mp_obj_get_type_str(mp_obj_t o_in);
+mp_obj_type_t *mp_obj_get_type(mp_const_obj_t o_in);
+const char *mp_obj_get_type_str(mp_const_obj_t o_in);
 bool mp_obj_is_subclass_fast(mp_const_obj_t object, mp_const_obj_t classinfo); // arguments should be type objects
+mp_obj_t mp_instance_cast_to_native_base(mp_const_obj_t self_in, mp_const_obj_t native_type);
 
 void mp_obj_print_helper(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t o_in, mp_print_kind_t kind);
 void mp_obj_print(mp_obj_t o, mp_print_kind_t kind);
diff --git a/py/objboundmeth.c b/py/objboundmeth.c
index 85094add6..9bbd34e9d 100644
--- a/py/objboundmeth.c
+++ b/py/objboundmeth.c
@@ -39,6 +39,17 @@ typedef struct _mp_obj_bound_meth_t {
     mp_obj_t self;
 } mp_obj_bound_meth_t;
 
+#if MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_DETAILED
+STATIC void bound_meth_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t o_in, mp_print_kind_t kind) {
+    mp_obj_bound_meth_t *o = o_in;
+    print(env, "<bound_method %p ", o);
+    mp_obj_print_helper(print, env, o->self, PRINT_REPR);
+    print(env, ".");
+    mp_obj_print_helper(print, env, o->meth, PRINT_REPR);
+    print(env, ">");
+}
+#endif
+
 mp_obj_t bound_meth_call(mp_obj_t self_in, uint n_args, uint n_kw, const mp_obj_t *args) {
     mp_obj_bound_meth_t *self = self_in;
 
@@ -65,6 +76,9 @@ mp_obj_t bound_meth_call(mp_obj_t self_in, uint n_args, uint n_kw, const mp_obj_
 const mp_obj_type_t bound_meth_type = {
     { &mp_type_type },
     .name = MP_QSTR_bound_method,
+#if MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_DETAILED
+    .print = bound_meth_print,
+#endif
     .call = bound_meth_call,
 };
 
diff --git a/py/objlist.c b/py/objlist.c
index 4432b2447..9e30ebb4a 100644
--- a/py/objlist.c
+++ b/py/objlist.c
@@ -153,6 +153,24 @@ STATIC mp_obj_t list_binary_op(int op, mp_obj_t lhs, mp_obj_t rhs) {
 STATIC mp_obj_t list_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
     if (value == MP_OBJ_NULL) {
         // delete
+#if MICROPY_ENABLE_SLICE
+        if (MP_OBJ_IS_TYPE(index, &mp_type_slice)) {
+            mp_obj_list_t *self = self_in;
+            machine_uint_t start, stop;
+            if (!mp_seq_get_fast_slice_indexes(self->len, index, &start, &stop)) {
+                assert(0);
+            }
+
+            int len_adj = start - stop;
+            //printf("Len adj: %d\n", len_adj);
+            assert(len_adj <= 0);
+            mp_seq_replace_slice_no_grow(self->items, self->len, start, stop, self->items/*NULL*/, 0, mp_obj_t);
+            // Clear "freed" elements at the end of list
+            mp_seq_clear(self->items, self->len + len_adj, self->len, sizeof(*self->items));
+            self->len += len_adj;
+            return mp_const_none;
+        }
+#endif
         mp_obj_t args[2] = {self_in, index};
         list_pop(2, args);
         return mp_const_none;
diff --git a/py/objstr.c b/py/objstr.c
index 80b0cf876..33bfcc375 100644
--- a/py/objstr.c
+++ b/py/objstr.c
@@ -54,6 +54,11 @@ STATIC mp_obj_t mp_obj_new_str_iterator(mp_obj_t str);
 STATIC mp_obj_t mp_obj_new_bytes_iterator(mp_obj_t str);
 STATIC mp_obj_t str_new(const mp_obj_type_t *type, const byte* data, uint len);
 STATIC NORETURN void bad_implicit_conversion(mp_obj_t self_in);
+STATIC NORETURN void arg_type_mixup();
+
+STATIC bool is_str_or_bytes(mp_obj_t o) {
+    return MP_OBJ_IS_STR(o) || MP_OBJ_IS_TYPE(o, &mp_type_bytes);
+}
 
 /******************************************************************************/
 /* str                                                                        */
@@ -535,7 +540,8 @@ enum { LSTRIP, RSTRIP, STRIP };
 
 STATIC mp_obj_t str_uni_strip(int type, uint n_args, const mp_obj_t *args) {
     assert(1 <= n_args && n_args <= 2);
-    assert(MP_OBJ_IS_STR(args[0]));
+    assert(is_str_or_bytes(args[0]));
+    const mp_obj_type_t *self_type = mp_obj_get_type(args[0]);
 
     const byte *chars_to_del;
     uint chars_to_del_len;
@@ -545,7 +551,9 @@ STATIC mp_obj_t str_uni_strip(int type, uint n_args, const mp_obj_t *args) {
         chars_to_del = whitespace;
         chars_to_del_len = sizeof(whitespace);
     } else {
-        assert(MP_OBJ_IS_STR(args[1]));
+        if (mp_obj_get_type(args[1]) != self_type) {
+            arg_type_mixup();
+        }
         GET_STR_DATA_LEN(args[1], s, l);
         chars_to_del = s;
         chars_to_del_len = l;
@@ -589,7 +597,7 @@ STATIC mp_obj_t str_uni_strip(int type, uint n_args, const mp_obj_t *args) {
     assert(last_good_char_pos >= first_good_char_pos);
     //+1 to accomodate the last character
     machine_uint_t stripped_len = last_good_char_pos - first_good_char_pos + 1;
-    return mp_obj_new_str(orig_str + first_good_char_pos, stripped_len, false);
+    return str_new(self_type, orig_str + first_good_char_pos, stripped_len);
 }
 
 STATIC mp_obj_t str_strip(uint n_args, const mp_obj_t *args) {
@@ -1326,9 +1334,12 @@ STATIC mp_obj_t str_count(uint n_args, const mp_obj_t *args) {
 }
 
 STATIC mp_obj_t str_partitioner(mp_obj_t self_in, mp_obj_t arg, machine_int_t direction) {
-    assert(MP_OBJ_IS_STR(self_in));
-    if (!MP_OBJ_IS_STR(arg)) {
-        bad_implicit_conversion(arg);
+    if (!is_str_or_bytes(self_in)) {
+        assert(0);
+    }
+    mp_obj_type_t *self_type = mp_obj_get_type(self_in);
+    if (self_type != mp_obj_get_type(arg)) {
+        arg_type_mixup();
     }
 
     GET_STR_DATA_LEN(self_in, str, str_len);
@@ -1349,9 +1360,9 @@ STATIC mp_obj_t str_partitioner(mp_obj_t self_in, mp_obj_t arg, machine_int_t di
     const byte *position_ptr = find_subbytes(str, str_len, sep, sep_len, direction);
     if (position_ptr != NULL) {
         machine_uint_t position = position_ptr - str;
-        result[0] = mp_obj_new_str(str, position, false);
+        result[0] = str_new(self_type, str, position);
         result[1] = arg;
-        result[2] = mp_obj_new_str(str + position + sep_len, str_len - position - sep_len, false);
+        result[2] = str_new(self_type, str + position + sep_len, str_len - position - sep_len);
     }
 
     return mp_obj_new_tuple(3, result);
@@ -1586,6 +1597,10 @@ STATIC void bad_implicit_conversion(mp_obj_t self_in) {
     nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "Can't convert '%s' object to str implicitly", mp_obj_get_type_str(self_in)));
 }
 
+STATIC void arg_type_mixup() {
+    nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "Can't mix str and bytes arguments"));
+}
+
 uint mp_obj_str_get_hash(mp_obj_t self_in) {
     // TODO: This has too big overhead for hash accessor
     if (MP_OBJ_IS_STR(self_in) || MP_OBJ_IS_TYPE(self_in, &mp_type_bytes)) {
@@ -1632,7 +1647,7 @@ const char *mp_obj_str_get_str(mp_obj_t self_in) {
 }
 
 const char *mp_obj_str_get_data(mp_obj_t self_in, uint *len) {
-    if (MP_OBJ_IS_STR(self_in)) {
+    if (is_str_or_bytes(self_in)) {
         GET_STR_DATA_LEN(self_in, s, l);
         *len = l;
         return (const char*)s;
diff --git a/py/objtuple.c b/py/objtuple.c
index 7d4e87755..ca65b28e3 100644
--- a/py/objtuple.c
+++ b/py/objtuple.c
@@ -99,12 +99,20 @@ mp_obj_t mp_obj_tuple_make_new(mp_obj_t type_in, uint n_args, uint n_kw, const m
 
 // Don't pass MP_BINARY_OP_NOT_EQUAL here
 STATIC bool tuple_cmp_helper(int op, mp_obj_t self_in, mp_obj_t another_in) {
-    assert(MP_OBJ_IS_TYPE(self_in, &mp_type_tuple));
-    if (!MP_OBJ_IS_TYPE(another_in, &mp_type_tuple)) {
-        return false;
+    mp_obj_type_t *self_type = mp_obj_get_type(self_in);
+    if (self_type->getiter != tuple_getiter) {
+        assert(0);
     }
+    mp_obj_type_t *another_type = mp_obj_get_type(another_in);
     mp_obj_tuple_t *self = self_in;
     mp_obj_tuple_t *another = another_in;
+    if (another_type->getiter != tuple_getiter) {
+        // Slow path for user subclasses
+        another = mp_instance_cast_to_native_base(another, &mp_type_tuple);
+        if (another == MP_OBJ_NULL) {
+            return false;
+        }
+    }
 
     return mp_seq_cmp_objs(op, self->items, self->len, another->items, another->len);
 }
diff --git a/py/objtype.c b/py/objtype.c
index 345eee714..c579477db 100644
--- a/py/objtype.c
+++ b/py/objtype.c
@@ -333,6 +333,9 @@ STATIC void instance_convert_return_attr(mp_obj_t self, mp_obj_t member, mp_obj_
         // return a bound method, with self being the type of this object
         dest[0] = ((mp_obj_static_class_method_t*)member)->fun;
         dest[1] = mp_obj_get_type(self);
+    } else if (MP_OBJ_IS_TYPE(member, &mp_type_type)) {
+        // Don't try to bind types
+        dest[0] = member;
     } else if (mp_obj_is_callable(member)) {
         // return a bound method, with self being this object
         dest[0] = member;
@@ -842,6 +845,15 @@ STATIC mp_obj_t mp_builtin_isinstance(mp_obj_t object, mp_obj_t classinfo) {
 
 MP_DEFINE_CONST_FUN_OBJ_2(mp_builtin_isinstance_obj, mp_builtin_isinstance);
 
+mp_obj_t mp_instance_cast_to_native_base(mp_const_obj_t self_in, mp_const_obj_t native_type) {
+    mp_obj_type_t *self_type = mp_obj_get_type(self_in);
+    if (!mp_obj_is_subclass_fast(self_type, native_type)) {
+        return MP_OBJ_NULL;
+    }
+    mp_obj_instance_t *self = (mp_obj_instance_t*)self_in;
+    return self->subobj[0];
+}
+
 /******************************************************************************/
 // staticmethod and classmethod types (probably should go in a different file)
 
diff --git a/py/runtime.c b/py/runtime.c
index 1479d8cba..a2de2d75b 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -840,6 +840,9 @@ void mp_load_method_maybe(mp_obj_t base, qstr attr, mp_obj_t *dest) {
                 // return a bound method, with self being the type of this object
                 dest[0] = ((mp_obj_static_class_method_t*)elem->value)->fun;
                 dest[1] = mp_obj_get_type(base);
+            } else if (MP_OBJ_IS_TYPE(elem->value, &mp_type_type)) {
+                // Don't try to bind types
+                dest[0] = elem->value;
             } else if (mp_obj_is_callable(elem->value)) {
                 // return a bound method, with self being this object
                 dest[0] = elem->value;
diff --git a/tests/basics/class_store_class.py b/tests/basics/class_store_class.py
new file mode 100644
index 000000000..60f65220d
--- /dev/null
+++ b/tests/basics/class_store_class.py
@@ -0,0 +1,47 @@
+# Inspired by urlparse.py from CPython 3.3 stdlib
+# There was a bug in MicroPython that under some conditions class stored
+# in instance attribute later was returned "bound" as if it was a method,
+# which caused class constructor to receive extra argument.
+try:
+    from collections import namedtuple
+except ImportError:
+    from _collections import namedtuple
+
+_DefragResultBase = namedtuple('DefragResult', 'foo bar')
+
+class _ResultMixinStr(object):
+    def encode(self):
+        return self._encoded_counterpart(*(x.encode() for x in self))
+
+class _ResultMixinBytes(object):
+    def decode(self):
+        return self._decoded_counterpart(*(x.decode() for x in self))
+
+class DefragResult(_DefragResultBase, _ResultMixinStr):
+    pass
+
+class DefragResultBytes(_DefragResultBase, _ResultMixinBytes):
+    pass
+
+
+DefragResult._encoded_counterpart = DefragResultBytes
+DefragResultBytes._decoded_counterpart = DefragResult
+
+# Due to differences in type and native subclass printing,
+# the best thing we can do here is to just test that no exceptions
+# happen
+
+#print(DefragResult, DefragResult._encoded_counterpart)
+#print(DefragResultBytes, DefragResultBytes._decoded_counterpart)
+
+o1 = DefragResult("a", "b")
+#print(o1, type(o1))
+o2 = DefragResultBytes("a", "b")
+#print(o2, type(o2))
+
+#print(o1._encoded_counterpart)
+_o1 = o1.encode()
+print(_o1[0], _o1[1])
+#print(_o1, type(_o1))
+
+print("All's ok")
diff --git a/tests/basics/int1.py b/tests/basics/int1.py
index 2daef9bf0..e8a0a0468 100644
--- a/tests/basics/int1.py
+++ b/tests/basics/int1.py
@@ -46,6 +46,7 @@ print(int('0B100', 2))
 print(int('0100', 2))
 print(int(' \t 0o12', 8))
 print(int('0o12  \t  ', 8))
+print(int(b"12", 10))
 
 
 def test(value, base):
diff --git a/tests/basics/list_slice_assign.py b/tests/basics/list_slice_assign.py
index f88052046..baa9a0081 100644
--- a/tests/basics/list_slice_assign.py
+++ b/tests/basics/list_slice_assign.py
@@ -11,6 +11,9 @@ print(l)
 l = list(x)
 l[1:3] = []
 print(l)
+l = list(x)
+del l[1:3]
+print(l)
 
 l = list(x)
 l[:3] = [10, 20]
@@ -18,6 +21,9 @@ print(l)
 l = list(x)
 l[:3] = []
 print(l)
+l = list(x)
+del l[:3]
+print(l)
 
 l = list(x)
 l[:-3] = [10, 20]
@@ -25,3 +31,6 @@ print(l)
 l = list(x)
 l[:-3] = []
 print(l)
+l = list(x)
+del l[:-3]
+print(l)
diff --git a/tests/basics/string_partition.py b/tests/basics/string_partition.py
index ad70d0250..fe0070a65 100644
--- a/tests/basics/string_partition.py
+++ b/tests/basics/string_partition.py
@@ -27,3 +27,14 @@ except ValueError:
     print("Raised ValueError")
 else:
     print("Did not raise ValueError")
+
+# Bytes
+print(b"abba".partition(b'b'))
+try:
+    print(b"abba".partition('b'))
+except TypeError:
+    print("Raised TypeError")
+try:
+    print("abba".partition(b'b'))
+except TypeError:
+    print("Raised TypeError")
diff --git a/tests/basics/string_strip.py b/tests/basics/string_strip.py
index 8e03eff93..4684c2a24 100644
--- a/tests/basics/string_strip.py
+++ b/tests/basics/string_strip.py
@@ -10,3 +10,13 @@ print('www.example.com'.lstrip('cmowz.'))
 
 print('   spacious   '.rstrip())
 print('mississippi'.rstrip('ipz'))
+
+print(b'mississippi'.rstrip(b'ipz'))
+try:
+    print(b'mississippi'.rstrip('ipz'))
+except TypeError:
+    print("TypeError")
+try:
+    print('mississippi'.rstrip(b'ipz'))
+except TypeError:
+    print("TypeError")
diff --git a/tests/basics/subclass_native_cmp.py b/tests/basics/subclass_native_cmp.py
new file mode 100644
index 000000000..1a095bfa1
--- /dev/null
+++ b/tests/basics/subclass_native_cmp.py
@@ -0,0 +1,9 @@
+# Test calling non-special method inherited from native type
+
+class mytuple(tuple):
+    pass
+
+t = mytuple((1, 2, 3))
+print(t)
+print(t == (1, 2, 3))
+print((1, 2, 3) == t)