An inmate who punched an officer in the head in an unprovoked attack in a Leeds prison has had more time added to his sentence.
Mark Walker carried out the attack on the woman moments after he was involved in a fight with another inmate at HMP Wealstun.
Leeds Crown Court previously heard the prison officer went to intervene in an "altercation" between Walker and the other prisoner on D Wing on the morning of August 29 last year.
Prosecutor Carmel Pearson said Walker was standing in the doorway of his cell when the officer got there and the other prisoner was being detained on the floor by one of her colleagues.
Miss Pearson said Walker was being aggressive and the officer managed to calm him down.
The attack on her took place as she was escorting him to another wing moments later.
The officer dropped something and bent down to pick it up as she was taking the inmate through some gates.
Walker punched her once to the forehead without warning.
Miss Pearson said: "She was shocked and alarmed because she did not anticipate he would behave like that.
"He hit her once and she felt pain to the forehead. A large lump emerged on her forehead."
As she fell back, he struck her two further times. Walker was detained by another officer and taken to a segregation unit.
The officer received treatment on the medical wing. She was off work for 30 days after the attack.
In a statement, she described how it was the worst incident of violence she had experienced in 15 years as a prison officer.
Walker, 28, of no fixed address, pleaded guilty at an early stage to assault occasioning actual bodily harm.
He has previous convictions for assault and drugs offences.
Phillip Morris, mitigating, said his client had lost his temper and the attack was not premediated.
He added: "Sadly for him his record reveals a degree of violence."
Walker was given an eight-month prison sentence on Tuesday.
