An inmate has been handed a further 18 weeks behind bars after throwing a bucket of urine and faeces over a prison officer.
Nathan Willoughby, 29, poured the human waste over the guard during an incident at HMP Woodhill at Milton Keynes on October 8, 2016.
A summons for him was authorised on March 16 this year.
Willoughby pleaded guilty to battery at Milton Keynes Magistrates' Court on June 27.
He is currently locked up at HMP Onley near Rugby, where he will stay for the extended prison term.
Speaking after sentencing, Thames Valley Police Detective Sergeant Simon Tyas said: "Thames Valley Police takes prison crime very seriously and recognises the lasting effects these type of particularly unpleasant assaults can have.
"The magistrates commented it was an 'extremely unpleasant assault'.
"This conviction sends a clear message such behaviour will not be tolerated and the courts will take such offending very seriously.
"Engaging in such behaviour will lead to extra time being put on sentences."