MoviePass filed a patent infringement lawsuit Friday against Sinemia, alleging that its rival subscription service has stolen many of its key features.

Both services allow customers to see movies in theaters in exchange for a discounted monthly fee. In the lawsuit, MoviePass accuses its rival of copying features of its mobile app that are the subject of two patents, both issued to MoviePass in 2013.

The MoviePass app verifies that subscribers are at the theater using their phone’s location data. MoviePass also uses a subscription card to redeem tickets. Sinemia’s app and card operate in such a similar fashion that they infringe on the patents, MoviePass argues.

“Sinemia’s infringement has harmed MoviePass’ existing customer relationships, has harmed MoviePass’ ability to obtain new customers and form new customer relationships, and has harmed MoviePass’ standing in the movie-subscription marketplace,” the lawsuit alleges.

MoviePass has exploded in popularity, going from 12,000 to 1.5 million in the course of five months, according to the suit. The service allows customers to see one standard 2D movie per day for $9.95 per month.

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Sinemia allows users to see two movies per month — including 3D and IMax movies — for $9.99. Sinemia could not be immediately reached for comment.

MoviePass laid out detailed allegations of infringement in two exhibits, which can be viewed here and here.