diff --git a/extmod/machine_mem.c b/extmod/machine_mem.c
index e0649290ef..b80eaea998 100644
--- a/extmod/machine_mem.c
+++ b/extmod/machine_mem.c
@@ -60,7 +60,7 @@ STATIC void machine_mem_print(const mp_print_t *print, mp_obj_t self_in, mp_prin
     mp_printf(print, "<%u-bit memory>", 8 * self->elem_size);
 }
 
-STATIC mp_obj_t machine_mem_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
+STATIC mp_obj_t machine_mem_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value, mp_obj_t instance) {
     // TODO support slice index to read/write multiple values at once
     machine_mem_obj_t *self = MP_OBJ_TO_PTR(self_in);
     if (value == MP_OBJ_NULL) {
diff --git a/extmod/modbtree.c b/extmod/modbtree.c
index 8b76885809..cfc614c137 100644
--- a/extmod/modbtree.c
+++ b/extmod/modbtree.c
@@ -246,7 +246,7 @@ STATIC mp_obj_t btree_iternext(mp_obj_t self_in) {
     }
 }
 
-STATIC mp_obj_t btree_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
+STATIC mp_obj_t btree_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value, mp_obj_t instance) {
     mp_obj_btree_t *self = MP_OBJ_TO_PTR(self_in);
     if (value == MP_OBJ_NULL) {
         // delete
diff --git a/extmod/moductypes.c b/extmod/moductypes.c
index 9eea30bf3e..2165152eaf 100644
--- a/extmod/moductypes.c
+++ b/extmod/moductypes.c
@@ -518,7 +518,7 @@ STATIC void uctypes_struct_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
     }
 }
 
-STATIC mp_obj_t uctypes_struct_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t value) {
+STATIC mp_obj_t uctypes_struct_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t value, mp_obj_t instance) {
     mp_obj_uctypes_struct_t *self = MP_OBJ_TO_PTR(self_in);
 
     if (value == MP_OBJ_NULL) {
diff --git a/ports/unix/modjni.c b/ports/unix/modjni.c
index 8ec5ae54d9..4aefb2476f 100644
--- a/ports/unix/modjni.c
+++ b/ports/unix/modjni.c
@@ -241,7 +241,7 @@ STATIC void get_jclass_name(jobject obj, char *buf) {
     check_exception();
 }
 
-STATIC mp_obj_t jobject_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
+STATIC mp_obj_t jobject_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value, mp_obj_t instance) {
     mp_obj_jobject_t *self = self_in;
     mp_uint_t idx = mp_obj_get_int(index);
     char class_name[64];
diff --git a/py/obj.c b/py/obj.c
index 6177f74b55..94c509be65 100644
--- a/py/obj.c
+++ b/py/obj.c
@@ -488,15 +488,14 @@ mp_obj_t mp_obj_len_maybe(mp_obj_t o_in) {
 }
 
 mp_obj_t mp_obj_subscr(mp_obj_t base, mp_obj_t index, mp_obj_t value) {
+    return mp_obj_subscr_impl(base, index, value, base);
+}
+
+mp_obj_t mp_obj_subscr_impl(mp_obj_t base, mp_obj_t index, mp_obj_t value, mp_obj_t instance) {
     mp_obj_type_t *type = mp_obj_get_type(base);
-    mp_obj_t instance = base;
-    // If we got an MP_OBJ_SENTINEL as the type, then we got called by instance_subscr
-    if (type == MP_OBJ_SENTINEL) {
-        instance = ((mp_obj_t *)base)[1];
-        type = mp_obj_get_type(((mp_obj_t *)base)[2]);
-    }
+
     if (type->subscr != NULL) {
-        mp_obj_t ret = type->subscr(instance, index, value);
+        mp_obj_t ret = type->subscr(base, index, value, instance);
         // May have called port specific C code. Make sure it didn't mess up the heap.
         assert_heap_ok();
         if (ret != MP_OBJ_NULL) {
@@ -551,7 +550,7 @@ STATIC mp_obj_t generic_it_iternext(mp_obj_t self_in) {
     mp_obj_type_t *type = mp_obj_get_type(self->obj);
     mp_obj_t current_length = type->unary_op(MP_UNARY_OP_LEN, self->obj);
     if (self->cur < MP_OBJ_SMALL_INT_VALUE(current_length)) {
-        mp_obj_t o_out = type->subscr(self->obj, MP_OBJ_NEW_SMALL_INT(self->cur), MP_OBJ_SENTINEL);
+        mp_obj_t o_out = type->subscr(self->obj, MP_OBJ_NEW_SMALL_INT(self->cur), MP_OBJ_SENTINEL, self->obj);
         self->cur += 1;
         return o_out;
     } else {
diff --git a/py/obj.h b/py/obj.h
index cf4216d02f..edeeb2a4b5 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -444,7 +444,7 @@ typedef mp_obj_t (*mp_call_fun_t)(mp_obj_t fun, size_t n_args, size_t n_kw, cons
 typedef mp_obj_t (*mp_unary_op_fun_t)(mp_unary_op_t op, mp_obj_t);
 typedef mp_obj_t (*mp_binary_op_fun_t)(mp_binary_op_t op, mp_obj_t, mp_obj_t);
 typedef void (*mp_attr_fun_t)(mp_obj_t self_in, qstr attr, mp_obj_t *dest);
-typedef mp_obj_t (*mp_subscr_fun_t)(mp_obj_t self_in, mp_obj_t index, mp_obj_t value);
+typedef mp_obj_t (*mp_subscr_fun_t)(mp_obj_t self_in, mp_obj_t index, mp_obj_t value, mp_obj_t instance);
 typedef mp_obj_t (*mp_getiter_fun_t)(mp_obj_t self_in, mp_obj_iter_buf_t *iter_buf);
 
 // Buffer protocol
@@ -708,6 +708,7 @@ mp_obj_t mp_obj_id(mp_obj_t o_in);
 mp_obj_t mp_obj_len(mp_obj_t o_in);
 mp_obj_t mp_obj_len_maybe(mp_obj_t o_in); // may return MP_OBJ_NULL
 mp_obj_t mp_obj_subscr(mp_obj_t base, mp_obj_t index, mp_obj_t val);
+mp_obj_t mp_obj_subscr_impl(mp_obj_t base, mp_obj_t index, mp_obj_t val, mp_obj_t instance);
 mp_obj_t mp_generic_unary_op(mp_unary_op_t op, mp_obj_t o_in);
 
 // cell
diff --git a/py/objarray.c b/py/objarray.c
index 9114a63c5a..70e57f1901 100644
--- a/py/objarray.c
+++ b/py/objarray.c
@@ -396,7 +396,7 @@ STATIC mp_obj_t array_extend(mp_obj_t self_in, mp_obj_t arg_in) {
 STATIC MP_DEFINE_CONST_FUN_OBJ_2(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) {
+STATIC mp_obj_t array_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t value, mp_obj_t instance) {
     if (value == MP_OBJ_NULL) {
         // delete item
         // TODO implement
diff --git a/py/objdict.c b/py/objdict.c
index 683fcb748e..c13ad88e5d 100644
--- a/py/objdict.c
+++ b/py/objdict.c
@@ -174,7 +174,7 @@ mp_obj_t mp_obj_dict_get(mp_obj_t self_in, mp_obj_t index) {
     }
 }
 
-STATIC mp_obj_t dict_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
+STATIC mp_obj_t dict_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value, mp_obj_t instance) {
     if (value == MP_OBJ_NULL) {
         // delete
         mp_obj_dict_delete(self_in, index);
diff --git a/py/objlist.c b/py/objlist.c
index ea38e64e55..b0c62a6ee6 100644
--- a/py/objlist.c
+++ b/py/objlist.c
@@ -158,7 +158,7 @@ STATIC mp_obj_t list_binary_op(mp_binary_op_t 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) {
+STATIC mp_obj_t list_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value, mp_obj_t instance) {
     if (value == MP_OBJ_NULL) {
         // delete
 #if MICROPY_PY_BUILTINS_SLICE
diff --git a/py/objrange.c b/py/objrange.c
index 30d55c56cd..f8b960900b 100644
--- a/py/objrange.c
+++ b/py/objrange.c
@@ -158,7 +158,7 @@ STATIC mp_obj_t range_binary_op(mp_binary_op_t op, mp_obj_t lhs_in, mp_obj_t rhs
 }
 #endif
 
-STATIC mp_obj_t range_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
+STATIC mp_obj_t range_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value, mp_obj_t instance) {
     if (value == MP_OBJ_SENTINEL) {
         // load
         mp_obj_range_t *self = MP_OBJ_TO_PTR(self_in);
diff --git a/py/objstr.c b/py/objstr.c
index 6ef9a15b5e..3d2cb338fe 100644
--- a/py/objstr.c
+++ b/py/objstr.c
@@ -431,7 +431,7 @@ const byte *str_index_to_ptr(const mp_obj_type_t *type, const byte *self_data, s
 #endif
 
 // This is used for both bytes and 8-bit strings. This is not used for unicode strings.
-STATIC mp_obj_t bytes_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
+STATIC mp_obj_t bytes_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value, mp_obj_t instance) {
     mp_obj_type_t *type = mp_obj_get_type(self_in);
     GET_STR_DATA_LEN(self_in, self_data, self_len);
     if (value == MP_OBJ_SENTINEL) {
diff --git a/py/objstrunicode.c b/py/objstrunicode.c
index 30000a51e7..e299266831 100644
--- a/py/objstrunicode.c
+++ b/py/objstrunicode.c
@@ -197,7 +197,7 @@ const byte *str_index_to_ptr(const mp_obj_type_t *type, const byte *self_data, s
     return s;
 }
 
-STATIC mp_obj_t str_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
+STATIC mp_obj_t str_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value, mp_obj_t instance) {
     mp_obj_type_t *type = mp_obj_get_type(self_in);
     assert(type == &mp_type_str);
     GET_STR_DATA_LEN(self_in, self_data, self_len);
diff --git a/py/objtuple.c b/py/objtuple.c
index ed13cdcef2..625c53bdd3 100644
--- a/py/objtuple.c
+++ b/py/objtuple.c
@@ -177,7 +177,7 @@ mp_obj_t mp_obj_tuple_binary_op(mp_binary_op_t op, mp_obj_t lhs, mp_obj_t rhs) {
     }
 }
 
-mp_obj_t mp_obj_tuple_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
+mp_obj_t mp_obj_tuple_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value, mp_obj_t instance) {
     if (value == MP_OBJ_SENTINEL) {
         // load
         mp_obj_tuple_t *self = MP_OBJ_TO_PTR(self_in);
diff --git a/py/objtuple.h b/py/objtuple.h
index 7f20ab7b6f..4df3aeded9 100644
--- a/py/objtuple.h
+++ b/py/objtuple.h
@@ -45,7 +45,7 @@ extern const mp_obj_type_t mp_type_tuple;
 void mp_obj_tuple_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind);
 mp_obj_t mp_obj_tuple_unary_op(mp_unary_op_t op, mp_obj_t self_in);
 mp_obj_t mp_obj_tuple_binary_op(mp_binary_op_t op, mp_obj_t lhs, mp_obj_t rhs);
-mp_obj_t mp_obj_tuple_subscr(mp_obj_t base, mp_obj_t index, mp_obj_t value);
+mp_obj_t mp_obj_tuple_subscr(mp_obj_t base, mp_obj_t index, mp_obj_t value, mp_obj_t instance);
 mp_obj_t mp_obj_tuple_getiter(mp_obj_t o_in, mp_obj_iter_buf_t *iter_buf);
 
 extern const mp_obj_type_t mp_type_attrtuple;
diff --git a/py/objtype.c b/py/objtype.c
index 7d41b86560..41ebe7b61e 100644
--- a/py/objtype.c
+++ b/py/objtype.c
@@ -823,7 +823,7 @@ STATIC void mp_obj_instance_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
     }
 }
 
-STATIC mp_obj_t instance_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
+STATIC mp_obj_t instance_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value, mp_obj_t instance) {
     mp_obj_instance_t *self = MP_OBJ_TO_PTR(self_in);
     mp_obj_t member[2] = {MP_OBJ_NULL};
     struct class_lookup_data lookup = {
@@ -850,8 +850,7 @@ STATIC mp_obj_t instance_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value
         meth_args = 3;
     }
     if (member[0] == MP_OBJ_SENTINEL) {
-        mp_obj_t args[3] = {MP_OBJ_SENTINEL, self_in, self->subobj[0]};
-        return mp_obj_subscr(args, index, value);
+        return mp_obj_subscr_impl(self->subobj[0], index, value, instance);
     } else if (member[0] != MP_OBJ_NULL) {
         mp_obj_t args[3] = {self_in, index, value};
         // TODO probably need to call mp_convert_member_lookup, and use mp_call_method_n_kw
diff --git a/py/opmethods.c b/py/opmethods.c
index 247fa5bbc8..d906ddb6a3 100644
--- a/py/opmethods.c
+++ b/py/opmethods.c
@@ -29,19 +29,19 @@
 
 STATIC mp_obj_t op_getitem(mp_obj_t self_in, mp_obj_t key_in) {
     mp_obj_type_t *type = mp_obj_get_type(self_in);
-    return type->subscr(self_in, key_in, MP_OBJ_SENTINEL);
+    return type->subscr(self_in, key_in, MP_OBJ_SENTINEL, self_in);
 }
 MP_DEFINE_CONST_FUN_OBJ_2(mp_op_getitem_obj, op_getitem);
 
 STATIC mp_obj_t op_setitem(mp_obj_t self_in, mp_obj_t key_in, mp_obj_t value_in) {
     mp_obj_type_t *type = mp_obj_get_type(self_in);
-    return type->subscr(self_in, key_in, value_in);
+    return type->subscr(self_in, key_in, value_in, self_in);
 }
 MP_DEFINE_CONST_FUN_OBJ_3(mp_op_setitem_obj, op_setitem);
 
 STATIC mp_obj_t op_delitem(mp_obj_t self_in, mp_obj_t key_in) {
     mp_obj_type_t *type = mp_obj_get_type(self_in);
-    return type->subscr(self_in, key_in, MP_OBJ_NULL);
+    return type->subscr(self_in, key_in, MP_OBJ_NULL, self_in);
 }
 MP_DEFINE_CONST_FUN_OBJ_2(mp_op_delitem_obj, op_delitem);
 
diff --git a/shared-bindings/_pixelbuf/PixelBuf.c b/shared-bindings/_pixelbuf/PixelBuf.c
index aeed6f5043..851c3a2762 100644
--- a/shared-bindings/_pixelbuf/PixelBuf.c
+++ b/shared-bindings/_pixelbuf/PixelBuf.c
@@ -348,7 +348,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_1(pixelbuf_pixelbuf_show_obj, pixelbuf_pixelbuf_s
 //|
 //|     Sets the pixel value at the given index.
 //|
-STATIC mp_obj_t pixelbuf_pixelbuf_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t value) {
+STATIC mp_obj_t pixelbuf_pixelbuf_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t value, mp_obj_t instance) {
     if (value == MP_OBJ_NULL) {
         // delete item
         // slice deletion
@@ -410,7 +410,7 @@ STATIC mp_obj_t pixelbuf_pixelbuf_subscr(mp_obj_t self_in, mp_obj_t index_in, mp
                 }
             }
             if (self->auto_write)
-                call_show(self_in, 's');
+                call_show(instance, 's');
             return mp_const_none;
             #else
             return MP_OBJ_NULL; // op not supported
@@ -430,7 +430,7 @@ STATIC mp_obj_t pixelbuf_pixelbuf_subscr(mp_obj_t self_in, mp_obj_t index_in, mp
             pixelbuf_set_pixel(self->buf + offset, self->two_buffers ? self->rawbuf + offset : NULL,
                 self->brightness, value, &self->byteorder, self->byteorder.is_dotstar);
             if (self->auto_write)
-                call_show(self_in, 'i');
+                call_show(instance, 'i');
             return mp_const_none;
         }
     }
diff --git a/shared-bindings/displayio/Bitmap.c b/shared-bindings/displayio/Bitmap.c
index 91c17f2d13..764313e1ec 100644
--- a/shared-bindings/displayio/Bitmap.c
+++ b/shared-bindings/displayio/Bitmap.c
@@ -133,7 +133,7 @@ const mp_obj_property_t displayio_bitmap_height_obj = {
 //|
 //|       bitmap[0,1] = 3
 //|
-STATIC mp_obj_t bitmap_subscr(mp_obj_t self_in, mp_obj_t index_obj, mp_obj_t value_obj) {
+STATIC mp_obj_t bitmap_subscr(mp_obj_t self_in, mp_obj_t index_obj, mp_obj_t value_obj, mp_obj_t instance) {
     if (value_obj == mp_const_none) {
         // delete item
         mp_raise_AttributeError(translate("Cannot delete values"));
diff --git a/shared-bindings/displayio/Group.c b/shared-bindings/displayio/Group.c
index dd7600eb9c..2288026dcd 100644
--- a/shared-bindings/displayio/Group.c
+++ b/shared-bindings/displayio/Group.c
@@ -310,7 +310,7 @@ STATIC mp_obj_t group_unary_op(mp_unary_op_t op, mp_obj_t self_in) {
 //|
 //|       del group[0]
 //|
-STATIC mp_obj_t group_subscr(mp_obj_t self_in, mp_obj_t index_obj, mp_obj_t value) {
+STATIC mp_obj_t group_subscr(mp_obj_t self_in, mp_obj_t index_obj, mp_obj_t value, mp_obj_t instance) {
     displayio_group_t *self = native_group(self_in);
 
     if (MP_OBJ_IS_TYPE(index_obj, &mp_type_slice)) {
diff --git a/shared-bindings/displayio/Palette.c b/shared-bindings/displayio/Palette.c
index dda58e3c53..491f9343b5 100644
--- a/shared-bindings/displayio/Palette.c
+++ b/shared-bindings/displayio/Palette.c
@@ -95,7 +95,7 @@ STATIC mp_obj_t group_unary_op(mp_unary_op_t op, mp_obj_t self_in) {
 //|       palette[2] = b'\xff\xff\x00\x00'          # set using 4 bytes
 //|       palette[3] = bytearray(b'\x00\x00\xFF')   # set using a bytearay of 3 or 4 bytes
 //|
-STATIC mp_obj_t palette_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t value) {
+STATIC mp_obj_t palette_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t value, mp_obj_t instance) {
     if (value == MP_OBJ_NULL) {
         // delete item
         return MP_OBJ_NULL; // op not supported
diff --git a/shared-bindings/displayio/TileGrid.c b/shared-bindings/displayio/TileGrid.c
index 288eb4b236..5acf8496f8 100644
--- a/shared-bindings/displayio/TileGrid.c
+++ b/shared-bindings/displayio/TileGrid.c
@@ -349,7 +349,7 @@ const mp_obj_property_t displayio_tilegrid_pixel_shader_obj = {
 //|
 //|       grid[0,0] = 10
 //|
-STATIC mp_obj_t tilegrid_subscr(mp_obj_t self_in, mp_obj_t index_obj, mp_obj_t value_obj) {
+STATIC mp_obj_t tilegrid_subscr(mp_obj_t self_in, mp_obj_t index_obj, mp_obj_t value_obj, mp_obj_t instance) {
     displayio_tilegrid_t *self = native_tilegrid(self_in);
 
 
diff --git a/shared-bindings/nvm/ByteArray.c b/shared-bindings/nvm/ByteArray.c
index 31bedeacc0..5ac46b260c 100644
--- a/shared-bindings/nvm/ByteArray.c
+++ b/shared-bindings/nvm/ByteArray.c
@@ -70,7 +70,7 @@ STATIC const mp_rom_map_elem_t nvm_bytearray_locals_dict_table[] = {
 
 STATIC MP_DEFINE_CONST_DICT(nvm_bytearray_locals_dict, nvm_bytearray_locals_dict_table);
 
-STATIC mp_obj_t nvm_bytearray_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t value) {
+STATIC mp_obj_t nvm_bytearray_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t value, mp_obj_t instance) {
     if (value == MP_OBJ_NULL) {
         // delete item
         // slice deletion
diff --git a/shared-bindings/pulseio/PulseIn.c b/shared-bindings/pulseio/PulseIn.c
index 8b69109f04..5947329a54 100644
--- a/shared-bindings/pulseio/PulseIn.c
+++ b/shared-bindings/pulseio/PulseIn.c
@@ -272,7 +272,7 @@ STATIC mp_obj_t pulsein_unary_op(mp_unary_op_t op, mp_obj_t self_in) {
 //|       pulses = pulseio.PulseIn(pin)
 //|       print(pulses[0])
 //|
-STATIC mp_obj_t pulsein_subscr(mp_obj_t self_in, mp_obj_t index_obj, mp_obj_t value) {
+STATIC mp_obj_t pulsein_subscr(mp_obj_t self_in, mp_obj_t index_obj, mp_obj_t value, mp_obj_t instance) {
     if (value == mp_const_none) {
         // delete item
         mp_raise_AttributeError(translate("Cannot delete values"));