Adele knows the sound wasn’t right during her Grammy Awards performance of “All I Ask” and she’s gone on Twitter to explain what went wrong.

“The piano mics fell onto the piano strings … ,” she wrote on Twitter after Monday’s show. “It made it sound out of tune.”

Recording Academy President Neil Portnow adds that when the show switched to a backup sound system during the song that also caused the audio to drop for several seconds.

Social media exploded with complaints about sound quality immediately after Adele’s performance. Some posters said it looked as though something on stage was distracting her.