The San Francisco 49ers and safety Antoine Bethea have reached agreement on a $23 million deal, according to sources.

On Wednesday, the Niners confirmed a four-year deal but did not disclose contract figures.

Bethea started every game he played in during his eight seasons with the Indianapolis Colts.

He had 110 tackles, the second-highest total of his career, last season along with two interceptions and a sack.

Bethea has had at least 100 tackles in each of the past six seasons.

He tweeted about his new team Tuesday afternoon.

Glad to be a Niner!! Going to the Bay!!! - Antoine Bethea (@Tweez41) March 11, 2014

He also tweeted thanks to Colts fans for supporting him.

Indy it's been real... Fans and city showed me nothing but love my eight years there and greeted me w/ open arms Appreciate all the support! - Antoine Bethea (@Tweez41) March 11, 2014

ESPN NFL Insider Adam Schefter and ESPN.com Colts reporter Mike Wells contributed to this report.