Generate Structures Option Doesn't Affect Nether Fortresses

When a world is generated, you are given the option to disable structures under the world options menu. Nether Fortresses are structures, but they are not disabled. I have not included any images, as there is no reason to post random images of Nether Fortresses. This is annoying for custom maps, where Blazes/Wither Skeletons are spawning where they are not supposed to.