Keeping Mark Zuckerberg safe is expensive.

Facebook paid its CEO an additional $13 million for his personal security and travel costs in 2018, according to a proxy filing on Friday. That included a new $10 million pre-tax allowance for additional security costs such as security guards, equipment, services and residential improvements.

"He is synonymous with Facebook and, as a result, negative sentiment regarding our company is directly associated with, and often transferred to, Mr. Zuckerberg," said the filing.

Like many wealthy CEOs, Zuckerberg receives an official salary of $1 a year. He also did not receive bonuses or stock awards in 2018. However, Zuckerberg's total compensation jumped from $9.1 million in 2017 to $22.6 million in 2018 in order to cover the increase in security costs for the high-profile CEO.

The increase is partially the result of specific threats against Zuckerberg and Facebook's (FB)high visibility, according to the company.

Facebook pays for Zuckerberg and his family's personal security at his homes and when he travels. Approximately $2.6 million of Zuckerberg's compensation package in 2018 was for private aircraft travel, which the company said was part of the security program.

The company is entering the second year of a seemingly non-stop series of scandals. It has been under fire for everything from personal privacy issues following revelations that data-firm Cambridge Analytica collected information on 87 million Facebook users, to enabling the spread of white supremacy and hate speech on the platform. Those events have drawn a large amount of exposure for the company and its 34-year-old co-founder.

"Mr. Zuckerberg is one of the most-recognized executives in the world, in large part as a result of the size of our user base and our continued exposure to global media, legislative, and regulatory attention," said the filing.

The filing said Facebook also increased the amount of money it put towards COO Sheryl Sandberg's personal security by $1.1 million.

Zuckerberg is one of the richest people in the world and is worth just over $70 billion, according to the Bloomberg Billionaire's index.