The London company that makes the Rubik's Cube has sued two US companies for selling what it alleges is a knock-off of the classic puzzle.
Rubik's Brand Limited says retailer Toys "R" Us and manufacturer Duncan Toys are violating its trademark and hurting its reputation with an "imitation twist puzzle cube".
It has asked a US court to stop the companies from selling the toys.
It is also seeking damages from profits from the puzzle.
The Rubik's Cube was invented by a Hungarian professor in 1974, and has sold more than 100 million copies worldwide.
The lawsuit was filed Monday in a federal court in New York.
It alleges that Duncan Toys, a unit of Wisconsin-based Flambeau, makes products that mimic the appearance of the Rubik's Cube, but with slight alterations, such as white instead of black borders.
Rubik's said the differences are confusing to customers and dilute its brand.
Duncan said the allegations are without merit, and the company intends to vigorously defend itself.
Toys "R" Us said it was aware of the lawsuit and is working with Duncan to determine the next steps.
The Duncan's 3x3 Quick Cube is available on the Toys "R" Us website for $4.99, about a third of what the classic Rubik's Cube costs.
Rubik's is no stranger to fights over its brand.
Last year the European Court of Justice ruled that the puzzle should be governed not by a trademark but by a patent, which protects inventions for a certain amount of time.