The problem states: The probability of a man telling the truth is = $3/4$. He rolls a dice and claims he got a six. What is the probability that he actually got a six?

And my textbook solves this using Bayes' theorem and gets $3/8$ as the answer.

The way I'm looking at it is: The probability that he really got what he's claiming (a six) should be equal to the probability of him telling the truth which = $3/4$. Where am I going wrong here?