Whats the ruling ?

We played a home tournament yesterday and the following situation came up :

UTG raised allin preflop, and the BB asked how many chips he had. The allin guy counted said that he had around 2000 chips, and the BB decided to call.

Then they flipped their cards over and it was KK for UTG and 77 for the BB.
Then another played realised that UTG had miscounted his chips and that he actually had 3800 chips.
The BB then said that he is not calling... Because he would have never called it in the first place if it would have been counted right at the start.

He still has to call right ?