It is proved that if k and d are positive integers such that the product of
any two distinct elements of the set
{F-2k, F2k+2, F2k+4, d}
increased by 1 is a perfect square, then d has to be 4F(2k+1)F(2k+2)F(2k+3)
. This is a generalization of the theorem of Baker and Davenport for k = 1.