module MsPortal.Controls.Base.ItemList { export interface Interface { // Removing this line fixes the constructor of ItemValue options: ViewModel; } export class ItemValue { constructor(value: T) { } } export class ViewModel extends ItemValue { } } // Generates: /* declare module MsPortal.Controls.Base.ItemList { interface Interface { options: ViewModel; } class ItemValue { constructor(value: T); } class ViewModel extends ItemValue { } } */