Fixing Facebook will be a long-term project, according to Chief Executive Mark Zuckerberg.

“To be clear, addressing these issues is more than a one-year challenge,” Zuckerberg said in a Facebook post, according to a Bloomberg report on Friday.

“For some of these issues, like election interference or harmful speech, the problems can never fully be solved.”

Still, the CEO said he was “proud of the progress we’ve made” in protecting users’ privacy and in weeding out “fake news” this year.

“We’ve fundamentally altered our DNA to focus more on preventing harm in all our services,” he wrote in the post.

Shares of Facebook have fallen almost 40 percent from their 52-week high of $218.62 in July.

On Friday, the stock closed at $133.20, down $1.32, or 1 percent.