Weird shader dark spots when using normal maps

So, I've been trying to get tf2 characters into unity, and so far the shaders I've found work really well. However, if I point lights at the models, they get wierd dark blotches when I use normal maps

vs with no normal maps

The shader code itself is apparently a bit outdated, and can be found here: http://leodomingues.com/2016/05/team-fortress-2-toon-shader-in-unity/