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As "Star Trek 3" began production in Vancouver, Canada earlier this week, Paramount has signed two lead stars for a potential fourth installment, according to The Hollywood Reporter. The site reports that Chris Pine and Zachary Quinto, who play Captain Kirk and Mr. Spock respectively, have granted an option for "Star Trek 4" as the studio renegotiated their deals.

Sources tell the site that Paramount and Skydance Entertainment "recently completed last-minute renegotiations with [Chris and Zachary], a move that has added as much as $10 million to $15 million to the budget." Chris, who earned $600,000 in 2009's "Star Trek", $1.5 million for "Star Trek Into Darkness" and $3 million for "Star Trek 3", reportedly scored $6 million for the fourth movie.

According to the sources, Paramount ultimately made some concessions to the original "Star Trek" actors including Chris, Zachary, Zoe Saldana, Simon Pegg, Karl Urban, Anton Yelchin and John Cho as the actors are getting more successful and more expensive. The studio originally wanted to give nominal raises to the actors based on their 2007 contract, but their representatives argued that seven years had passed since then.

Under California law, a personal services contract cannot bind someone for more than seven years. That meant the cast's original deals were arguably invalid as of 2014.

Sources say that a condition of the raises for Chris and Zachary was because the studio was granted options for a fourth movie in order to keep Kirk and Spock intact.