A thug who was jailed for life after he kicked a man to death over a kebab, in attack on prison officer.
Dean Logan, 27, thumped Alan Murphy at HMP Shotts, as a row erupted into violence.
The guard was left with bruising to his head while the yob was thrown into solitary confinement by prison bosses.
Logan appeared at Hamilton Sheriff Court and admitted the assault in March last year.
He was given three months by Sheriff Anthony Deutsch who told him it would run alongside his current life term for murder.
Depute fiscal Alice Carey said: "The witness sustained bruising to the side of his head after being punched by the accused."
Logan, who represented himself in court, said: "I was segregated for a number of months and lost wages.
"I admit I punched the officer but there was a reason behind it, prison is a difficult place."
Sheriff Deutsch said: "I see from your record that the last time you did something like this you were admonished so I will mark this with a concurrent sentence.
"But what I would say to you is that this kind of thing will affect any parole hearings you may face in the future."
Logan was part of a gang who set upon Nachatter Singh Bola, 36, in a vicious unprovoked attack as he made his way home with a takeaway.
Logan, along with Dillon Cherrie and Stewart Patterson, all admitted murdering Bola at the High Court in Edinburgh.
They repeatedly kicked and stamped on their victim, who was visiting relatives in Scotland from India, in Renfrew in July 2010 after they chased him and he fell to the ground.
The teenage gang had all been drinking and taking valium before they launched their attack.
Bola died in hospital after he suffered a lack of oxygen to the brain and developed pneumonia and multiple organ failure.
Logan and Cherrie were ordered to spend at least nine years behind bars by judge Lady Dorrian, while Patterson was handed a minimum term of 10-and-a-half-years.