Generating Typescript with the multiplatform plugin

I am using the kotlin multiplatform plugin 1.4 M2 and cant seem to work out how to generate typescript files (.d.ts) instead of js

A snippet of my build is below
kotlin {
sourceSets {
commonMain {
js(IR) {

In the directory build\js\packages$project-name\kotlin I can see a js file but no .d.ts

Has anyone managed to generate a .d.ts file?