DORTMUND, Germany (AP) — A stadium selfie could soon cost fans of German soccer giant Borussia Dortmund after the club announced plans to reward those who leave their phones alone during the game.

Dortmund is offering signed jerseys and gift cards for club merchandise to fans who use an app which measures how often they unlock their phones at its stadium.

Arguing that “more and more fans are annoyed by selfies, streaming, and social media in the stands,” Dortmund says supporters can volunteer to use a “fan mode” in the club's app, starting Saturday with a home game against Eintracht Frankfurt.

Fan mode will measure how often the phone is unlocked during the game — not counting the halftime break — and award points to people based on how little they use the device, with prizes on offer for those with the most points. Each time the phone is unlocked, the user loses points.

“Over 81,000 people in the stadium, singing, cheering, and holding their breath together: this here and now is irreplaceable,” Dortmund CEO Carsten Cramer said in a statement Thursday.

The rewards scheme and app are voluntary and there's no ban on fans using their phones.

German soccer is famed for its vocal fanbase, especially Dortmund's vast and loud “Yellow Wall” standing section.

The club's stance is part of a backlash in German soccer against attempts to turn its stadium atmosphere into social media content, especially by influencers using professional camera equipment.

Second-division club Hertha Berlin said this month it was banning “commercially produced and monetized” video productions from its games, while allowing fans to take photos and videos for personal use.

Another club, Dynamo Dresden, said in August it would ban commercial filming for social media, saying it wanted to ensure fans felt comfortable at the game and to protect the club's TV rights deals.