On Saturday night, singer Kesha joined electronic music artist Zedd on stage in a surprise visit during the Coachella Valley Music and Arts Festival. The singer’s performance—her first mainstream show since she filed suit against producer Dr. Luke—was one of a number of appearances not publicized as part of the original lineup and added something sorely lacking to the festival stage: a female voice.

For the ninth year in a row, Coachella’s headliners are exclusively male. In fact, there have only one woman has headlined the festival since it was founded in 1999: Bjork, who was at the top of the bill in 2002 and 2007.

Mainstage acts aside, women are slightly better represented in the overall lineup, with about a quarter of the 167 total acts fronted by women this year, according to a tally by the Los Angeles Times. Not great, but better than last year’s 16%.

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However, these tallies don’t include surprise guests, who were plentiful during the festival’s first weekend. A number of these unexpected performances came from women; in addition to Kesha, last-minute adds included Rihanna, Lorde, Janelle Monae, Jillian Herve of Lion Babe, and Aluna Francis of AlunaGeorge.

It is unclear whether the addition of these female performers was a response to previous calls for more women, or just a happy coincidence (Coachella representatives have not yet responded to a request for comment).

While it’s great to see more women guesting and gracing Coachella’s smaller stages, putting female artists in those high-profile headliner slots remains important. As the LA Times‘ Mikael Woods writes, Coachella “has metastasized over the decade and a half since its founding into a closely watched cultural event, one that helps set agendas, not only in music but also in media, branding and style.”

Female artists deserve to be on the agenda, too.