A heat exchanger for a gas turbine engine includes a heat exchanger body having a first surface and a second surface oriented at least partially at an oblique angle relative to the first surface. The heat exchanger body defines a plenum extending between the first and second surfaces. Furthermore, the heat exchanger body defines a fluid passage extending through the second surface such that the fluid passage is in fluid communication with the plenum. The fluid passage, in turn, includes first and second portions. The first portion intersects the plenum at an intersection and defines a line of projection extending normal to the second surface. The second portion defines a line of projection extending normal to the first surface. The fluid passage further includes a curved portion extending from the first portion to the second portion.