Örebro district court ruled in July to commute Flink's life sentence to 32 years, meaning that he would have been eligible for release within five years.
The court's ruling was appealed by the prosecutor but the ruling has been confirmed by the appeals court (Hovrätten), although the killer's prison term has been extended to 36 years.
Flink was originally sentenced to life in prison for seven murders and three attempted murders in Falun in 1994. The appeals court ruling now means that under Swedish parole conditions, Flink could be eligible for release in 2019.
Flink was 24 in June 1994 when he shot seven people to death and injured three others shots in the vicinity of Dalregementet in Falun, where he was stationed and held the rank of second lieutenant in the armed forces.
He had earlier argued with his girlfriend and was heavily intoxicated when he fired 51 rounds from his military-issued AK5 rifle, killing five women and two men aged 20 to 35 in a park in the centre of town.
Flink is currently housed in the closed prison in Beateberg, south of Stockholm.
In electing to commute Flink's sentence the Örebro court decided not to follow the Supreme Court's (Högsta domstolen) practice, under which culpability for murder receives between 18 and 24 years in prison. The punishment is higher partly because the law is based on the seriousness of each individual indictment.
However, the district court did refer to the Supreme Court's life sentence, in which a mitigating factor in Flink's case was that he could not control his actions due to psychosis.
The court also assessed Flink's risk of relapse and reached the conclusion that he has demonstrated exemplary behaviour while imprisoned and noted that he had completed 30 home leave visits without incident.