The 49ers have tendered a one-year contract to Mostert (knee), an exclusive-rights free agent, Eric Branch of the San Francisco Chronicle reports.
Primarily a special teamer, Mostert had six carries for 30 yards in 11 games last season, ultimately landing on injured reserve in late November due to a knee injury. He should be back to compete for a spot at the bottom of the depth chart, but there's not much reason to think he'll be a factor in the backfield, regardless of what happens with impending free agent Carlos Hyde.