The Prison Officers Association Scotland has become the first trade union to offer its full support to the Scottish self-government campaign.
At the representative body's conference in Peebles, delegates voted on a motion to voice their "frustration and dismay" at the Westminster government's pension arrangements and refusal to recognise prison officers as a key operational service like the police or fire brigade.
The supported motion also agreed that the best interest of prison officers will be served by an independent Scottish Government.
Blair Jenkins, independence campaign Yes Scotland's chief executive said: "Yes Scotland are delighted by the decision of the Prison Officers Association of Scotland to support a Yes vote in next year's referendum - the first union to declare its backing for independence so far.
"Their frustration with the failing and uncaring Westminster system chimes throughout Scotland, as too does their appreciation for what the devolved Scottish Parliament has been able to achieve in spite of limited powers.
"A Yes vote is the natural choice for the Prison Officers Association and for other trade union members throughout the country. There are benefits for public services that only a Yes vote can bring. With independence we will always get the governments we vote for - governments that are better placed to listen to the needs of the people of Scotland."
* More on the Scottish independence referendum from Ekklesia: http://www.ekklesia.co.uk/scottishindependence