I'm using reactive forms in angular 2 (4.1.2)

I have a boolean property which I don't want to have a default value but it should be required.

This is how I create my form:

constructor(private fb: FormBuilder) {

    this.form = this.fb.group({

        payedOvertime: [false, Validators.required],

    });

}

And my html:

<div class=form-group>

    <label>Payed overtime</label>

    <label>

        <input type=radio name=payedOvertime formControlName=payedOvertime [value]=true />Yes

    </label>

    <label>

        <input type=radio name=payedOvertime formControlName=payedOvertime [value]=false />No

    </label>

</div>

The problem is that while this works the radiobutton is preselected but I do not want that, rather it should have to be selected by clicking at one of the radio-buttons. If neither of the radiobuttons are clicked I want the form to be invalid.