The teenage killer of schoolboy Joe Geeling has had his sentence increased from 12 years to 15.
Joe Geeling was stabbed 16 times by Hamer
Michael Hamer, 15, repeatedly beat and stabbed 11-year-old Joe before dumping his body in a Greater Manchester park last March.
Hamer will now serve a minimum of 15 years of his life sentence for murder, the Court of Appeal has ruled.
Joe's father, Tom Geeling, said the decision was "a victory for common sense".
"At long last we feel we have achieved a more just sentence for our son's killer, he added.
"Michael Hamer will still be a relatively young man when he is released from prison, but our personal loss will remain forever.
"However, we feel this judgement sets an appropriate sentence and is a victory for common sense. Hopefully we can now draw a line under this side of events and try again to move on".
At his trial, Manchester Crown Court was told that Hamer lured Joe back to his house where he beat him with a frying pan before stabbing him to death.
After the attack, he dragged Joe's body downstairs, put it in a wheelie bin and took the bin to the park, where he hid it.
The appeal decision was made by Sir Igor Judge, Mr Justice Gray and Mr Justice Henriques, sitting in London, following submissions by the Attorney General Lord Goldsmith QC, who argued that the initial sentence was too lenient.
Sir Igor said it was a "fraught, worrying case".
He said the aggravating factors of the case included the "deliberate selection" of Joe, the sustained violence and the "calm efforts of concealment" by Hamer which "represent a formidable level of culpability and seriousness".
It had been accepted on Hamer's behalf during the course of mitigation that "he had attacked Joe after he had made some kind of sexual approach to him, which Joe had rejected".
Sir Igor said the trial judge was provided with a victim impact statement prepared by Joe's father: "We have read it with care and with sympathy.
"Joe's murder is catastrophic. It is indeed 'the worst nightmare' which any parent could be forced to suffer."
Hamer's minimum term was initially set at 12 years
A search was launched for Joe, a cystic fibrosis sufferer, after he failed to return home from St Gabriel's High School in Bury on the day he died.
His body was found hidden under debris in a gulley in Whitehead Park the next day.
Det Supt Martin Bottomley, who led the investigation into Joe's murder, said it had been "a long and difficult process for all the Geeling family".
He added: "I hope that they can now take some comfort in the fact that Hamer will be in custody for an appropriate length of time and also that their feeling that the original sentence was too lenient has been upheld."
Hamer, who had no previous convictions, was bullied at school and at the time of the killing was suffering from an adjustment disorder.