The Pittsburgh Penguins made some pickups on the first day of NHL free agency, signing defenseman Christian Ehrhoff, forward Blake Comeau and goaltender Thomas Greiss to a one-year contracts on Tuesday.

Ehrhoff's deal is worth $4 million for the 2014-15 season, according to TSN.

Ehrhoff, considered one of the best unrestricted free agent defensemen on the market this year, fills a need on the back line for the Penguins with Matt Niskanen becoming a free agent. Last season, Ehrhoff had six goals and 27 assists in 79 games for the Buffalo Sabres.

The Sabres bought out Ehrhoff's 10-year, $40 million contract on Sunday.

The 31-year-old's best season came in 2010 with the Vancouver Canucks when he had 50 points. Ehrhoff entered the NHL with the San Jose Sharks in 2003. He then spent two seasons each with the Canucks and Sabres.

The 28-year-old Comeau, who received $700,000, had five goals and 16 points in 61 games for the Columbus Blue Jackets last season. In 422 career games with the Jackets, New York Islanders and Calgary Flames, Comeau has 72 goals and 164 points.

Greiss, also 28, posted a 10-8-5 record with a 2.29 goals-against average and a .920 save percentage in 25 games for the Coyotes last season. He also had two shutouts.

In 69 career NHL games, Greiss has a 27-24-8 record with a 2.43 goals-against average and a .915 save percentage.