Institutional Shareholder Services (ISS) gave a boost to Tesla Motors’ plan to buy solar panel installer SolarCity for more than $2 billion by recommending that shareholders of both companies vote for the deal, the advisory firm said on Friday.

“The transaction is a necessary step towards TSLA’s goal of being an integrated sustainable energy company,” said ISS, an influential proxy advisory firm that recommends votes for contested situations and deals to institutional shareholders. “Additionally, it appears reasonable to assume that TSLA is paying a low to no premium to take over SCTY.”

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The deal has faced pressure from shareholders critical of the takeover plan, given the performance struggles at SolarCity scty and Tesla tsla founder Elon Musk’s prominent role at both companies.