Haxe SWC override getter/setter

// in Haxe I have this:

// MyRect.hx
    #if swc @:extern #end
    public var width(get, set):Int;

    #if swc @:getter(width) #end
    private function get_width() { return Std.int(rect.width); }

    #if swc @:setter(width) #end
    private function set_width(value:Int):Int { throw new Error("Cannot modify this property!"); return 0; }

// MyObject.hx
    private var _width:Int = 0;

    //#if swc @:getter(width) #end
    override private function get_width() { return _width; }

    //#if swc @:setter(width) #end
    override private function set_width(value:Int):Int
    {
        if (_width != value) {
            _width = value;
            update();
        }
        return value;
    }

// It compiles fine as a SWC (no compiler errors). But when I try to use the lib in AS3 I get:
// VerifyError: Error #1053: Illegal override of width in net.test.MyObject
//
// I've tried removing the override, or the getter/setter to no avail.
//
// Using extern/getter/setter has worked fine in other tests, but every time I used an override
// I get the mentioned error and don't know how to work around it.