GEOS 2 MAPSERVER PROBLEM

I tried upgrading GDAL and GEOS the other day, only to find that when I did so, MapServer kept complaining that

error while loading shared libraries: libgeos.so.2: cannot load shared object file: No such file or directory

when libgeos.so.2 was clearly where it should have been. Then I found this useful little note on the MS wiki. Translating the advice into Gentoo, I just ran env-update and everything worked again. Go fig.