The Paris prosecutor's office said on Sunday that a fifth person had died from their wounds following Tuesday's Strasbourg Christmas market shooting.
An official with the prosecutor's office said the victim was a Polish national and gave no other details.
"My brother Barto Pedro Orent-Niedzielski has just passed away. He thanks you for the love and strength you have given him," the brother of the 36-year-old victim from the Polish city of Katowice wrote on Facebook.
The gunman, Cherif Chekatt, was killed on Thursday night after firing on police, ending a two-day manhunt that involved more than 700 members of the security forces.
The 29-year-old attacked Christmas market shoppers armed with a gun and a knife on Dec. 11.
Orent-Niedzielski and his Italian friend Antonio Megalizzi had tried to stop Chekatt from entering a bar during Tuesday's assault, a close friend told AFP.
Megalizzi, 28, died from his injuries on Friday.
Nicknamed "Bartek", Orent-Niedzielski had lived in Strasbourg for 20 years, according to his friend.
11 people were also injured in the bloodbath, with several still in a critical condition.