diff --git a/extmod/modbtree.c b/extmod/modbtree.c
index ad845163d6..7cfa9c6afb 100644
--- a/extmod/modbtree.c
+++ b/extmod/modbtree.c
@@ -246,9 +246,7 @@ STATIC mp_obj_t btree_iternext(mp_obj_t self_in) {
     }
 }
 
-#pragma GCC diagnostic ignored "-Wunused-parameter"
 STATIC mp_obj_t btree_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
-    //mp_obj_btree_t *self = MP_OBJ_TO_PTR(self_in);
     mp_obj_btree_t *self = mp_instance_cast_to_native_base(self_in, &btree_type);
     if (value == MP_OBJ_NULL) {
         // delete
diff --git a/shared-bindings/_pixelbuf/PixelBuf.c b/shared-bindings/_pixelbuf/PixelBuf.c
index 6eb35c51ad..3e93190470 100644
--- a/shared-bindings/_pixelbuf/PixelBuf.c
+++ b/shared-bindings/_pixelbuf/PixelBuf.c
@@ -332,11 +332,11 @@ STATIC mp_obj_t pixelbuf_pixelbuf_unary_op(mp_unary_op_t op, mp_obj_t self_in) {
 
 //|   .. method:: show()
 //|
-//|     Does nothing unless subclassed.
+//|     Must be implemented in subclasses.
 //|
 
 STATIC mp_obj_t pixelbuf_pixelbuf_show(mp_obj_t self_in) {
-    return mp_const_none;
+    mp_raise_NotImplementedError(NULL);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(pixelbuf_pixelbuf_show_obj, pixelbuf_pixelbuf_show);