I had to run the command sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.8 20, but unfortunately I misstyped and wrote sudo update-alternatives --install /usr/bin/gcc gccc /usr/bin/gcc-4.8 20 (so gccc instead of gcc).
Now, when trying to run the regular command, it tells me the alternative link /usr/bin/gcc is allready managed by gcccc.
I've searched around but haven't found a solution yet.