Path to freedom

Suppose that you are a prisoner who is suddenly granted the right to be released, but only if you cope with this task: you have two doors, one of them leads to freedom, the other is the road to death.

Two guards are sitting, one of them being a liar, and the second always telling the truth; you don’t know which of them is who. You should, asking only one question to one of the guards, determine the path to freedom.

What question do you ask?