Frank Ocean dropped a late Valentine’s Day surprise on his Tumblr page Wednesday night: a cover of “Moon River,” the 1962 song written by Henry Mancini and Johnny Mercer and sung by Audrey Hepburn in the classic film “Breakfast at Tiffany’s.”

Posted above a caption that says simply “In the late nite,” the song is spare instrumentally — featuring just a gentle electric guitar and some atmospheric keyboards — but elaborate vocally, with multiple overlapping overdubs of Ocean’s voice woven together.

While of a piece with the spare structure of Ocean’s recent tracks and his 2016 album “Blonde,” the song’s open-hearted melody — written in a single octave specifically for Hepburn, who was not a trained singer — gives him plenty of room to roam vocally, and its optimistic mood contrasts with the often-bittersweet or skeptical tone of his own compositions.

It also also continues Ocean’s completely self-determined approach to releasing music whenever he feels like it, often on his Beats 1 radio show, “Blonded.” He used the station to premiere several songs in 2017, including “Provider” in August as well as “Biking (Solo)” and “RAF,” a collaboration with A$AP Rocky, earlier in the year. He performed a handful of concerts over the summer, including shows in New York and Los Angeles that were filmed by Spike Jonze and met with rapturous response from the audiences.