Orange County-based clothing company Lucky 13, which produces street wear, has sued the 24-year-old singer for trademark infringement.
The apparel brand has taken issue with Swift's use of the phrase, "Lucky 13," on her merchandise.
The "I Knew You Were Trouble" singer-songwriter has long associated herself with the number.
"I love the number 13," is the second line in her website bio and she often writes "13" on her hand during performances.
"I was born on the 13th. I turned 13 on Friday the 13th. My first album went gold in 13 weeks. My first #1 song had a 13-second intro," she said. "Every time I've won an award I've been seated in either the 13th seat, the 13th row, the 13th section or row M, which is the 13th letter," Swift told MTV News back in 2009.
"Basically whenever a 13 comes up in my life, it's a good thing," she said.
Not this time.
The suit, filed in California on Tuesday, wants profits from Swift's merchandising efforts and damages for the Lucky 13 brand.
"Swift's conduct has been and will continue to be malicious, fraudulent, deliberate, willfull, intentional, and in disregard of Plaintiffs' intellectual property rights," the suit reads. "There can be no doubt that Swift -- who has an extensive trademark portfolio and numerous business and licensing partners, and whose record label is even named the 'Big Machine' -- knows, understands and substantially profits from her carefully cultivated and meticulously managed trademarks and brand, image, and other intellectual property."