Victorian sex offenders who recklessly breach supervision orders will be thrown into jail for a mandatory 12 months.
Police will also be allowed to hold serious sex offenders for up to 72 hours without a charge - up from 10 hours - under new laws set to be introduced.
The changes come after Sean Christian Price, who had a history of violent sexual offending, murdered teenager Masa Vukotic in a Melbourne park last year.
He was on a supervision order at the time but had sentences for violent behaviour reduced.
"Tragically our system failed Masa Vukotic and her family," Premier Daniel Andrews told reporters on Tuesday.
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"I think this is a balanced approach, it's a tough approach of course."
A loophole in the previous system meant even if a serious sex offender committed a violent act they didn't breach their supervision order.
That will be closed and offenders who intentionally or recklessly breach their orders will be sent to jail for a mandatory 12 months.
If police think one of Victoria's 41 serious sex offenders living in the community is at risk of imminent offending they can be locked up for three days.
"Perhaps some civil libertarians will find it difficult but they didn't have to speak to Masa Vukotic's mother and explain to her that her daughter was gone ... because the system had failed," Mr Andrews said.
The new laws will also give police new search and seizure powers when supervising a serious sex offender.
The legislation was introduced into parliament on Tuesday.
Opposition corrections spokesman Ed O'Donohue said the opposition would examine the detail of the proposed new laws.
"(But) there is no point introducing new laws if we don't have more police to enforce them and a justice system that is strong enough to impose proper punishments," Mr O'Donohue said.
The premier said a review of the system that allowed Price out to murder Ms Vukotic will be released after his avenues for legal appeals have been exhausted.
