Issue between 4.0 and 4.1

So I have some good that works perfectly in 4.0 and lower, but it starts not working in 4.1, so I assume it must have to do with the new compiler.

I tried forcing it to use the old one with the flag -open64, but the code still does not work. Is there a way to make sure it is actually using the -open64 compiler after it completes?