A hollow fan blade for a gas turbine engine provides improved resistance to buckling without adding wall thickness. The hollow fan blade includes a pressure side wall and a suction side wall separated and supported by ribs. In the present invention, each wall segment between each adjacent pair of ribs is straight, not curved. At least some of the adjacent walls segments extend at non-parallel angles relative to one another to form the airfoil shape to the hollow fan blade. The resulting fan blade side walls have faceted surfaces, rather than a continuous smooth, curved surface. The straight wall segments between adjacent ribs can withstand higher compressive forces without buckling. As a result, the wall thickness can be reduced.