Aurelia Validation - Stop property name appearing in error message

I'm using the new aurelia-validation packages and when a validation fails the error message that is created contains the property name. Quite often the underlying property name isn't very user friendly so you don't want to show it on the page.

ValidationRules  
            .ensure('isDeliveryAddressValid').required()
            .on(this.order);

I have tried added a custom message to validation rules but this just appends something different on to my property name.

ValidationRules  
            .ensure('isDeliveryAddressValid').required({message:'must have a value.'})
            .on(this.order);

Is there a way to remove the property name from the validation error so my validation renderer can show a better message?