49-year-old Melvin Buckner was pronounced dead just before 6:20 p.m. on Sunday at OSF St. Francis Medical Center in Peoria.
He had been in the hospital for several days after allegedly being attacked by 29-year-old Christopher Croom out of Chicago.
Police said last week that a disturbance between the two led to the alleged stabbing incident in the 500 block of West Brooks Street just before midnight on Wednesday in Galesburg.
After initially issuing a warrant for attempted murder, Galesburg Police have now amended the warrant.
Croom is now wanted for First Degree Murder and Unlawful Use of a Weapon by a Felon.
Croom is still considered at large as of Monday. The victim has initially transported to Galesburg Cottage Hospital before being taken to Peoria for treatment.