Transmission spectrum of WASP-189b around the metastable helium triplet (vertical dashed red lines). Grey dots with error bars represent the entire transmission spectrum at native resolution, and cyan dots with uncertainties are the binned spectrum. No trace of metastable helium triplet is found in WASP-189b from atomic line inspection of its transmission spectrum, as expected given the theory of Oklopčić & Hirata (2018).