If you're lucky enough to catch Blake Mills on his current tour in support of 'Heigh Ho,' you might be treated to a cameo by none other than Fiona Apple.

On the tour's second night, while at Los Angeles' El Rey, Apple joined Mills onstage for a beautiful rendition of 'Don't Tell Our Friends About Me.' In the video below, Mills explains that he actually performed this song a few years ago when touring as support for Apple -- and she came up wit the idea to add a female part. The end result is an enchanting, if not all-to-real, song about a broken heart and the mending process.

A few days later in Seattle, Apple and Mills once again joined forces for 'Don't Tell Our Friends About Me' as well as 'It's Only Make Believe' and 'Seven.'

It looks as though Apple is a regular part of the 'Heigh Ho' tour, though it hasn't been officially confirmed by either side. Regardless, check out the fan-filmed videos below to see what to expect when Mills (and Apple?) rolls through your town.

Blake Mills and Fiona Apple -- Sept. 18, 2014 -- Los Angeles

Blake Mills and Fiona Apple -- Sept. 23, 2014 -- Seattle

Blake Mills Fall 2014 Tour
Sept. 26: St. Paul, Minn. -- Amsterdam Bar
Sept. 27: Evanston, Ill. -- Space
Sept. 28: Chicago, Ill. -- Mayne Stage
Sept. 30: Cambridge, Mass. -- The Sinclair
Oct. 1: New York, N.Y. -- (Le) Poisson Rouge
Oct. 6: Washington, D.C. -- The Hamilton
Oct. 8: Brooklyn, N.Y. -- Rough Trade
Oct. 9: Philadelphia, Penn. -- World Cafe Live
Oct. 13: London, England -- Bush Hall
Oct. 15: Paris, France -- Le Zebre De Belleville