Watch your back, Bernie!

Bernard Madoff's fellow inmates at a North Carolina federal prison — where the Ponzi schemer arrived last week — are discussing beating him up to boost their jailhouse reputations, The Post has learned.

"Some of the guys were talking about smacking him around a little, just to get the notoriety of it," said a source who has a relative locked up with the 71-year-old Madoff.

But other convicts have no beef with Madoff and are even a bit impressed by him and the way he has handled himself since arriving at the Butner, N.C., prison complex, the source said.

Some of his fellow inmates, in fact, respect him for being a stand-up guy who pleaded guilty without implicating any of the other people strongly suspected of helping him pull off the fraud that swindled more than 1,000 people out of more than $65 billion over two decades.

"He got a lot of respect from other inmates because he didn't tell on anybody, he didn't take everybody down with him," the source said.

"Some of the inmates admired that."

The source provided the first glimpse into Madoff's life behind bars — revealing his sadness at ruining his wife Ruth's life, his new "job" and his new diet.

Click here for more on this story from the New York Post.