How to use Object.defineProperty for getters in Typescript?

I have used an implementation as given below in JavaScript.

class Base {
    installGetters() {
        Object.defineProperty(this, 'add', {
            get() {
                return 5;
            }
        });
    }
}

class New extends Base {
    constructor() {
        super();
        this.installGetters();
    }

    someAddition() {
        return 10 + this.add;
    }
}

I have defined the getter property add in the function of the parent class – Base and used that property in child class New after calling the installGetters() function in the child class constructor. This works for JavaScript, but this.add is throwing an error in case of Typescript. Any help would be much appreciated.